And Ahaz said. By a plausible excuse he refuses the sign which the Lord offered to him. That excuse is, that he is unwilling to tempt the LORD; for he pretends to believe the words of the Prophet, and to ask nothing more from God than his word. Ungodliness is certainly detestable in the sight of God, and in like manner God unquestionably sets a high value on faith. Accordingly, if a man rely on his word alone, and disregard everything else, it might be thought that he deserves the highest praise; for there can be no greater perfection than to yield full submission and obedience to God. But a question arises. Do we tempt God, when we accept what he offers to us? Certainly not. Ahaz therefore speaks falsehood, when he pretends that he refuses the sign, because he is unwilling to tempt God; for there can be nothing fitter or more excellent than to obey God, and indeed it is the highest virtue to ask nothing beyond the word of God; and yet if God choose to add anything to his word, it ought not to be regarded as a virtue to reject this addition as superfluous. It is no small insult offered to God, when his goodness is despised in such a manner as if his proceedings towards us were of no advantage, and as if he did not know what it is that we chiefly need. We know that faith is chiefly commended on this ground, that it maintains obedience to him; but when we wish to be too wise, and despise anything that belongs to God, we are undoubtedly abominable before God, whatever excuse we may plead before men. While we believe the word of God, we ought not to despise the aids which he has been pleased to add for the purpose of strengthening our faith. For instance, the Lord offers to us in the gospel everything necessary for salvation; for when he brings us into a state of fellowship with Christ, the sum of all blessings is truly contained in him. What then is the use of Baptism and the Lord's Supper? Must they be regarded as superfluous? Not at all; for any one who shall actually, and without flattery, acknowledge his weakness, of which all from the least to the greatest are conscious, will gladly avail himself of those aids for his support. We ought indeed to grieve and lament, that the sacred truth of God needs assistance on account of the defect of our flesh; but since we cannot all at once remove this defect, any one who, according to his capacity shall believe the word, will immediately render full obedience to God. Let us therefore learn to embrace the signs along with the word, since it is not in the power of man to separate them. When Ahaz refuses the sign offered to him, by doing so he displays both his obstinacy and his ingratitude; for he despises what God had offered for the highest advantage. Hence also it is evident how far we ought to ask signs, namely, when God offers them to us; and therefore he who shall reject them when offered, must also reject the grace of God. In like manner fanatics of the present day disregard Baptism and the Lord's Supper, and consider them to be childish elements. They cannot do this without at the same time rejecting the whole gospel; for we must not separate those things which the Lord has commanded us to join. But a question may be asked, Is it not sometimes lawful to ask signs from the Lord? For we have an instance of this in Gideon, who wished to have his calling confirmed by some sign. (Judges 6:17.) The Lord granted his prayer, and did not disapprove of such a desire. I answer, though Gideon was not commanded by God to ask a sign, yet he did so, not at his own suggestion, but by an operation of the Holy Spirit. We must not abuse his example, therefore, so that each of us may freely allow himself that liberty; for so great is the forwardness of men that they do not hesitate to ask innumerable signs from God without any proper reason. Such effrontery ought therefore to be restrained, that we may be satisfied with those signs which the Lord offers to us. Now, there are two kinds of signs; for some are extraordinary, and may be called supernatural; such as that which the Prophet will immediately add, and that which, we shall afterwards see, was offered to Hezekiah. (Isaiah 38:7.) Some are ordinary, and in daily use among believers, such as Baptism and the Lord's Supper, which contain no miracle, or at least may be perceived by the eye or by some of the senses. What the Lord miraculously performs by his Spirit is unseen, but in those which are extraordinary the miracle itself is seen. Such is also the end and use of all signs; for as Gideon was confirmed by an astonishing miracle, so we are confirmed by Baptism and the Lord's Supper, though our eyes behold no miracle.

I will not ask - In this case Ahaz assumed the appearance of piety, or respect for the command of God. In Deuteronomy 6:16, it is written, 'Thou shalt not tempt the Lord thy God;' and Ahaz perhaps had this command in his eye. It was a professed reverence for God. But the true reason why he did not seek this sign was, that he had already entered into a negotiation with the king of Assyria to come and defend him; and that he was even stripping the temple of God of its silver and gold, to secure this assistance; 2-Kings 16:7-8. When people are depending on their own devices and resources, they are unwilling to seek aid from God; and it is not uncommon if they excuse their want of trust in him by some appearance of respect for religion.
Tempt - Try, or do a thing that shall provoke his displeasure, or seek his interposition in a case where he has not promised it. To tempt God is the same as to put him to the proof; to see whether he is able to perform what he proposed. It is evident, however, that here there would have been no "temptation" of God, since a sign had been offered him by the prophet in the name of God. 'The answer of Ahaz can be regarded either as one of bitter scorn, as if he had said, "I will not put thy God to the proof, in which he will be found lacking. I will not embarrass thee by taking thee at thy word;" or as the language of a hypocrite who assumes the mask of reverence for God and his command.' - "Hengstenberg." Chrysostom and Calvin regard the latter as the correct interpretation. If it be asked here "why" Ahaz did not put Isaiah to the test, and "secure," if possible, the divine confirmation to the assurance that Jerusalem would be safe, the following may be regarded as the probable reasons:
(1) He was secretly relying on the aid of Assyria. He believed that he could fortify the city, and distress the enemy by turning away the supply of water, so that they could not carry on a siege, and that all the further aid which he needed could be derived from the Assyrians.
(2) If the miracle had been "really performed," it would have been a proof that Yahweh was the true God a proof which Ahaz had no desire of witnessing. He was a gross idolater; and he was not anxious to witness a demonstration which would have convinced him of the folly and sin of his own course of life.
(3) If the miracle could not be performed, as Ahaz seems to have supposed would be the case, then it would have done much to unsettle the confidence of the people, and to have produced agitation and alarm. It is probable that a considerable portion of the people were worshippers of Yahweh, and were looking to him for aid. The pious, and the great mass of those who conformed to the religion of their fathers, would have been totally disheartened; and this was a result which Ahaz had no desire to produce.
(4) Michaelis has suggested another reason, drawn from the character of idolatry. According to the prevailing notions at that period, every nation had its own gods. Those of one people were more, and those of another less powerful; see Isaiah 10:10-11; Isaiah 36:18-20; Isaiah 37:10-13. If a miracle had been performed, Ahaz might have believed that it was performed by the god of the country, who might have had the disposition, but not the power, to defend him. It would have been to the mind of the idolater no proof that the god of Syria or Samaria was not more powerful, and might not have easily overcome him. Ahaz seems to have regarded Yahweh as such a God - as one of the numerous gods which were to be worshipped, and perhaps as not the most powerful of the tutelary divinities of the nations. This was certainly the view of the surrounding idolaters Isaiah 10:10-11; Isaiah 36:18-20; and it is highly probable that this view prevailed among the idolatrous Israelites.

But Ahaz said, I will not ask, neither will I (k) tempt the LORD.
(k) Not to believe God's word without a sign, is to tempt God, but to refuse a sign when God offers it for the aid and help of our infirmity is to rebel against him.

But Ahaz said, I will not ask,.... That is, a sign or miracle to be wrought; being unwilling to take the advice to be still and quiet, and make no preparation for war, or seek out for help from the Assyrians, and to rely upon the promise and power of God, and therefore chose not to have it confirmed by a sign; adding as an excuse,
neither will I tempt the Lord, by asking a sign; suggesting that this was contrary to the command of God, Deuteronomy 6:16 so pretending religion and reverence of God; whereas, to ask a sign of God, when it was offered, could not be reckoned a tempting him; but, on the contrary, to refuse one; when offered, argued great stubbornness and ingratitude, as Calvin well observes.

neither . . . tempt--hypocritical pretext of keeping the law (Deuteronomy 6:16); "tempt," that is, put God to the proof, as in Matthew 4:7, by seeking His miraculous interposition without warrant. But here there was the warrant of the prophet of God; to have asked a sign, when thus offered, would not have been a tempting of God. Ahaz' true reason for declining was his resolve not to do God's will, but to negotiate with Assyria, and persevere in his idolatry (2-Kings 16:7-8, 2-Kings 16:3-4, 2-Kings 16:10). Men often excuse their distrust in God, and trust in their own devices, by professed reverence for God. Ahaz may have fancied that though Jehovah was the God of Judea and could work a sign there, that was no proof that the local god of Syria might not be more powerful. Such was the common heathen notion (Isaiah 10:10-11; Isaiah 36:18-20).

I will not - By asking a sign, as if I questioned the truth of his word: but this was deep hypocrisy.