Then follows, Harden not your hearts By which words is intimated that our rebellion against God flows from no other fountain than willful wickedness, by which we obstruct the entrance of his grace, We have indeed by nature a heart of stone, and there is in all an innate hardness from the womb, which God alone can mollify and amend. That we, however, reject the voice of God, it happens through a spontaneous obstinacy, not through an external impulse, a fact of which every one is a witness to himself. Rightly, then, does the Spirit accuse all the unbelieving that they resist God, and that they are the teachers and authors of their own perverseness, so that they can throw the blame on none else. It is hence, however, absurdly concluded that we have, on the other hand, a free power to form the heart for God's service; nay rather, it must ever be the case with men, that they harden their heart until another be given them from heaven; for as we are bent towards wickedness, we shall never cease to resist God until we shall be tamed and subdued by his hand. As in the provocation, etc. It was for two reasons necessary for them to be reminded of the disobedience of their fathers; for as they were foolishly inflated on account of the glory of their race, they often imitated the vices of their fathers as though they were virtues, and defended themselves by their examples; and further, when they heard that their fathers were so disobedient to God, they were thus more fully taught that this admonition was not superfluous. As both these reasons existed even in the Apostle's time, he readily accommodated to his own purpose what had been formerly said by David, in order that those whom he addressed might not imitate their fathers too much. And hence may be learnt a general truth, that we are not to defer too much to the authority of the fathers lest it should draw us away from God; for if any fathers have ever been worthy of honor, no doubt the Jews possessed that preeminence; and yet David distinctly commanded their children to beware of being like them. And I have no doubt but that he referred to the history recorded in Exodus 17: for David uses here the two names which Moses relates were given to a certain place, mrvh Meribah, which means strife or provocation, and msh Massah, which means temptation. They tempted God by denying that he was in the midst of them, because they were distressed for want of water; and they also provoked him by contending with Moses. Though indeed they gave many examples of unbelief, yet David selected this in an especial manner, because it was more memorable then any other, and also, because in order of time it followed for the most part the rest, as it evidently appears from the fourth book of Moses, where from chap. 10 to 20 a series of many temptations is described; but this narrative is given in the twentieth chapter. This circumstance increased not a little the atrocity of their wickedness; for they had often experienced the power of God, and yet they perversely contended with him, and renounced all confidence in him: how great was their ingratitude! He then mentioned one particular instance instead of many.

Harden not your hearts - Do not render the heart insensible to the divine voice and admonition. A hard heart is that where the conscience is seared and insensible; where truth makes no impression; where no religious effect is produced by afflictions; where preaching is listened to without interest; and where the mind is unaffected by the appeals of friends. The idea here is, that a refusal to listen to the voice of God is connected with a hardening of the heart. It is in two ways:
(1) The very refusal to do this tends to harden it. And,
(2) in order to resist the appeals of God, people must resort to the means of "voluntarily" hardening the heart. This they do by setting themselves against the truth; by the excuses which they offer for not becoming Christians: by plunging into sin in order to avoid serious impressions; and by direct resistance of the Holy Spirit. No inconsiderable part of the efforts of sinners consists in endeavoring to produce insensibility in their minds to the truth and the appeals of God.
As in the provocation - Literally, "in the embittering" - ἐν τῶ παραπικρασμῶ en tō parapikrasmō. Then it means what embitters or provokes the mind - as disobedience. Here it refers to what they did to "embitter" the mind of God against them; that is to the course of conduct which was adopted to provoke him to wrath.
In the day of temptation - In the time of temptation - the word "day" being used here, as it is often, to denote an indefinite period, or "time" in general. The word "temptation" here refers to the various provocations by which they "tried" the patience of God. They rebelled against him; they did what put the divine patience and forbearance to a trial. It does not mean that they tempted God to do evil, but that his long-suffering was "tried" by their sins.
In the wilderness - The desert through which they passed. The word "wilderness" in the Scriptures commonly means a "desert;" see the notes at Matthew 3:1. "One provocation was in demanding bread at Sin; a second for want of water at Massah or Meribah; a third time at Sinai with the golden calf; a fourth time at Taberah for want of flesh; a fifth time at Kadesh when they refused to go up into Canaan, and the oath came that they should die in the wilderness. A like refusal may prevent us from entering into rest." - Dr. John P. Wilson, Manuscript Notes.

Harden not your hearts - Which ye will infallibly do, if ye will not hear his voice.
Provocation - Παραπικρασμος· From παρα, signifying intensity, and πικραινω, to make bitter; the exasperation, or bitter provocation. "The Israelites provoked God first in the wilderness of Sin, (Pelusium), when they murmured for want of bread, and had the manna given them, Exodus 16:4. From the wilderness of Sin they journeyed to Rephidim, where they provoked God a second time for want of water, and insolently saying, Is the Lord God among us or not? Exodus 17:2-9, on which account the place was called Massah and Meribah. See 1-Corinthians 10:4 (note), note 1. From Rephidim they went into the wilderness of Sinai, where they received the law, in the beginning of the third year from their coming out of Egypt. Here they provoked God again, by making the golden calf, Exodus 32:10. After the law was given they were commanded to go directly to Canaan, and take possession of the promised land, Deuteronomy 1:6, Deuteronomy 1:7 : God spake unto us in Horeb, saying, Ye have dwelt long enough in this mount: turn you, and take your journey, and go to the mount of the Amorites, and unto all the places nigh thereunto, in the plain, in the hills, and in the vales, and in the south, and by the seaside, to the land if the Canaanites, and unto Lebanon, and unto the great river, the river Euphrates. The Israelites, having received this order, departed from Horeb, and went forward three days' journey, Numbers 10:33, till they came to Taberah, Numbers 11:3, where they provoked God the fourth time, by murmuring for want of flesh to eat; and for that sin were smitten with a very great plague, Numbers 11:33; this place was called Kibroth-hattaavah, because there they buried the people who lusted. From Kibroth-hattaavah they went to Hazeroth, Numbers 11:35, and from thence into the wilderness of Paran, Numbers 12:16, to a place called Kadesh, Numbers 13:26. Their journey from Horeb to Kadesh is thus described by Moses, Deuteronomy 1:19-21 : And when we departed from Horeb, we went through all that great and terrible wilderness, which you saw by the way of the mountain of the Amorites, as the Lord our God commanded us; and, we came to Kadesh-barnea. And I said unto you, Ye are come unto the mountain of the Amorites, which the Lord our God doth give unto us. Behold, the Lord thy God hath set the land before thee; go up and possess it. But the people proposed to Moses to send spies, to bring them an account of the land, and of its inhabitants, Deuteronomy 1:22. These after forty days returned to Kadesh; and, except Caleb and Joshua, they all agreed in bringing an evil report of the land, Numbers 13:25-32; whereby the people were so discouraged that they refused to go up, and proposed to make a captain, and return into Egypt, Numbers 14:4. Wherefore, having thus shown an absolute disbelief of God's promises, and an utter distrust of his power, he sware that not one of that generation should enter Canaan, except Caleb and Joshua, but should all die in the wilderness, Numbers 14:20; Deuteronomy 1:34, Deuteronomy 1:35; and ordered them to turn, and get into the wilderness, by the way of the Red Sea. In that wilderness the Israelites, as Moses informs us, sojourned thirty-eight years, Deuteronomy 2:14 : And the space in which we came from Kadesh-barnea, until we were come over the brook Zereb, was thirty and eight years; until all the generation of the men of war were wasted out from among the host, as the Lord sware unto them. Wherefore, although the Israelites provoked God to wrath in the wilderness, from the day they came out of the land of Egypt until their arrival in Canaan, as Moses told them, Deuteronomy 9:7, their greatest provocation, the provocation in which they showed the greatest degree of evil disposition, undoubtedly was their refusing to go into Canaan from Kadesh. It was therefore very properly termed the bitter provocation and the day of temptation, by way of eminence; and justly brought on them the oath of God, excluding them from his rest in Canaan. To distinguish this from the provocation at Rephidim, it is called Meribah-Kadesh," Deuteronomy 32:51. See Dr. Macknight.

Harden not your hearts, as in the (g) provocation, in the day of temptation in the wilderness:
(g) In the day that they troubled the Lord, or struggled with him.

Harden not you hearts,.... There is a natural hardness of the heart; the heart of man is like a stone, destitute of spiritual life, motion, and activity; it is senseless, stupid, impenitent, stubborn, and inflexible, on which no impressions can be made, but by powerful grace: and there is an acquired, habitual, and voluntary hardness of heart, to which men arrive by various steps; as entertaining pleasing thoughts of sin; an actual commission of it, with frequency, till it becomes customary, and so habitual; an extenuation or justification of it, and so they become hardened against all reproofs and sermons, and to all afflictions and judgments; are insensible and past feeling, and openly declare for sin, and glory in it: and there is a hardness which God's people are liable to, and should guard against; and which is brought on by a neglect of private and public worship, and by keeping bad company, and through the ill examples of others, and by giving way to lesser sins; for all sin is of an hardening nature:
as in the provocation, in the day of temptation in the wilderness; the Jews provoked God in the wilderness by their unbelief, murmurings, ingratitude, and idolatry; and they tempted him there by distrusting his power and goodness; hence one of the places in which they murmured against him was called Massah and Meribah, Exodus 17:7 and it is an aggravation of their sin, that it was in the wilderness, after they had been just brought out of bondage into liberty, and had lately had such an instance of the power and goodness of God, in bringing them through the Red sea; and where they could have no human supplies, and therefore should have been entirely dependent on God, and trust in him.

Harden not your hearts--This phrase here only is used of man's own act; usually of God's act (Romans 9:18). When man is spoken of as the agent in hardening, the phrase usually is, "harden his neck," or "back" (Nehemiah 9:17).
provocation . . . temptation--"Massah-meribah," translated in Margin "tentation . . . chiding," or "strife" (Exodus 17:1-7). Both names seem to refer to that one event, the murmuring of the people against the Lord at Rephidim for want of water. The first offense especially ought to be guarded against, and is the most severely reproved, as it is apt to produce many more. Numbers 20:1-13 and Deuteronomy 33:8 mention a second similar occasion in the wilderness of Sin, near Kadesh, also called Meribah.
in the day--Greek, "according to the day of."

As in the provocation - When Israel provoked me by their strife and murmurings. In the day of temptation - When at the same time they tempted me, by distrusting my power and goodness. Exodus 17:7.