Thou shalt not fear for the terror of the night. The Psalmist continues to insist upon the truth which I have just adverted to, that, if we confide with implicit reliance upon the protection of God, we will be secure from every temptation and assault of Satan. It is of importance to remember, that those whom God has taken under his care are in a state of the most absolute safety. Even those who have reached the most advanced experience find nothing more difficult than to rely upon Divine deliverance; and more especially when, overtaken by some of the many forms in which danger and death await us in this world, doubts will insinuate themselves into our hearts, giving rise to fear and disquietude. There was reason, therefore, why the Psalmist should enter upon a specification of different evils, encouraging the Lord's people to look for more than one mode of deliverance, and to bear up under various and accumulated calamities. Mention is made of the fear of the night, because men are naturally apprehensive in the dark, or because the night exposes us to dangers of different kinds, and our fears are apt at such a season to magnify any sound or disturbance. The arrow, rather than another weapon, is instanced as flying by day, for the reason apparently that it shoots to a greater distance, and with such swiftness, that we can with difficulty escape it. The verse which follows states, though in different words, the same truth, that there is no kind of calamity which the shield of the Almighty cannot ward off and repel.

Thou shalt not be afraid for the terror by night - That which usually causes alarm at night - a sudden attack; an unexpected incursion of enemies; sudden disease coming on by night; or the pestilence which seems to love night, and to "walk in darkness." Any one of these things seems to be aggravated by night and darkness; and hence, we most dread them then. We cannot see their approach; we cannot measure their outlines; we know not the extent of the danger, or what may be the calamity.
Nor for the arrow that flieth by day - Whether shot from the bow of God - as pestilence and disease; or from the hand of man in battle. The idea is, that he that trusts in God will be calm. Compare the notes at Psalm 56:3.

The terror by night - Night is a time of terrors, because it is a time of treasons, plunder, robbery, and murder. The godly man lies down in peace, and sleeps quietly, for he trusts his body, soul, and substance, in the hand of God; and he knows that he who keepeth Israel neither slumbers nor sleeps. It may also mean all spiritual foes, - the rulers of the darkness of this world. I have heard the following petition in an evening family prayer: "Blessed Lord, take us into thy protection this night; and preserve us from disease, from sudden death, from the violence of fire, from the edge of the sword, from the designs of wicked men, and from the influence of malicious spirits!"
Nor for the arrow - The Chaldee translates this verse, "Thou shalt not fear the demons that walk by night; nor the arrow of the angel of death which is shot in the day time." Thou needest not to fear a sudden and unprovided-for death.

(e) Thou shalt not be afraid for the terror by night; [nor] for the arrow [that] flieth by day;
(e) The care that God has over his is sufficient to defend them from all dangers.

Thou shalt not be afraid for the terror by night,.... The terrible things that happen in the night; as fire, storms and tempests, invasion of enemies, murders, thefts, and, robberies: a good man, when he has committed himself and his family to the care and protection of God by prayer, has no reason to be anxiously careful of these things, or to indulge a slavish fear about them; see Psalm 3:5, the Targum is,
"thou shall not be afraid for the fear of devils that walk in the night:''
so Jarchi interprets this, and the next verse, of such; as do others of the Jewish writers: a man that trusts in the Lord need not be afraid of men or devils: a fear of evil spirits is natural to men, and very early appeared; perhaps it took its rise from the fatal affair of the fall of our first parents, through an intercourse with an evil spirit; and ever since has been imprinted on human nature an aversion to evil spirits, and a dread of them, and even of all spirits in general; see Job 4:13,
nor for the arrow that flieth by day; the judgments of God, such as the sword, famine, and pestilence; these are called the arrows of God, Deuteronomy 32:23 (q), because they move swiftly, come suddenly, and strike surely, and are open and visible; they are sent by the Lord, and are ordered and directed by him, and hit and hurt whom he pleases, and none else; and therefore such who dwell in the secret of the Lord, and under his shadow, need not be distressed about them: the Targum interprets it of the arrow of the angel of death, which he sends out in the day; see Hebrews 2:14, so Jarchi understands it of a demon that flies like an arrow.
(q) ---- , Homer. Iliad. 1. v. 51, 53.

terror--or, what causes it (Proverbs 20:2).
by night--then aggravated.
arrow--that is, of enemies.

By night - When evil accidents are most terrible and least avoidable. Arrow - The pestilence, or any such destructive calamity; such are frequently called God's arrows. By day - Thou shalt be kept from secret and open mischiefs.