The particle of negation in ver. 3 is not that used in ver. 4, but that which is employed in commands or wishes. The progress from subjective desire in ver. 3, to objective certainty of Divine help as expressed in ver. 4 and the remainder of the psalm, is best exhibited if the verbs in the former verse are translated as expressions of wish--"May He not," etc. Whether the speaker is taken to be the psalmist or another makes little difference to the force of ver. 3, which lays hold in supplication of the truth just uttered in ver. 2, and thereby gains a more assured certainty that it is true, as the following verses go on to declare. It is no drop to a lower mood to pass from assertion of God's help to prayer for it. Rather it is the natural progress of faith. Both clauses of ver. 3 become specially significant if this is a song for pilgrims. Their daily march and their nightly encampment will then be placed under the care of Jehovah, who will hold up their feet unwearied on the road and watch unslumbering over their repose. But such a reference is not necessary. The language is quite general. It covers the whole ground of toil and rest, and prays for strength for the one and quiet security in the other.
The remainder of the psalm expands the one thought of Jehovah the Keeper, with sweet reiteration, and yet comprehensive variation. First, the thought of the last clause of the preceding verse is caught up again. Jehovah is the keeper of the community, over which He watches with unslumbering care. He keeps Israel, so long as Israel keeps His law; for the word so frequently used here is the same as is continually employed for observance of the commandments. He had seemed to slumber while Israel was in exile, and had been prayed to awake, in many a cry from the captives. Now they have learned that He never slumbers: His power is unwearied, and needs no recuperation; His watchfulness is never at fault. But universal as is His care, it does not overlook the single defenceless suppliant. He is "_thy_ Keeper," and will stand at thy right hand, where helpers stand, to shield thee from all dangers. Men lose sight of the individual in the multitude, and the wider their benevolence or beneficence, the less it takes account of units; but God loves all because He loves each, and the aggregate is kept because each member of it is. The light which floods the universe gently illumines every eye. The two conceptions of defence and impartation of power are smelted together in the pregnant phrase of ver. 5_b_, "thy shade at thy right hand."
The notion of shelter from evils predominates in the remainder of the psalm. It is applied in ver. 6 to possible perils from physical causes: the fierce sunlight beat down on the pilgrim band, and the moon was believed, and apparently with correctness, to shed malignant influences on sleepers. The same antithesis of day and night, work and rest, which is found in ver. 3 appears again here. The promise is widened out in ver. 7 so as to be all-inclusive. "All evil" will be averted from him who has Jehovah for his keeper; therefore, if any so-called Evil comes, he may be sure that it is Good with a veil on. We should apply the assurances of the psalm to the interpretation of life, as well as take them for the antidote of fearful anticipations.
Equally comprehensive is the designation of that which is to be kept. It is "thy soul," the life or personal being. Whatever may be shorn away by the sharp shears of Loss, that will be safe; and if it is, nothing else matters very much. The individual soul is of large account in God's sight: He keeps it as a deposit entrusted to Him by faith. Much may go; but His hand closes round us when we commit ourselves into it, and none is able to pluck us thence.