The author of this psalm, and the occasion on which it was composed, are alike unknown. The psalm has no title; and there are no internal marks by which we can ascertain when, or by whom, it was written. It is very general in its application, and may have been composed with no particular reference to any event occurring at the time, as it is evident that it had no special reference to the circumstances of the writer. Though it follows a psalm composed by Moses, yet there is no reason to suppose that it was written by him, nor is there any particular resemblance to that psalm.
From some things in the psalm, as Psalms 91:3-5, Psalms 91:9,Psalms 91:11; it would appear to be not improbable that the psalm was composed with reference to some individual who was exposed to temptation, or to danger, either from secret enemies or from pestilence, and that it was intended to assure such an one that there was nothing to be feared if he put his trust in God. There is no evidence that it was designed to refer particularly to the Saviour. It is, indeed, applied to him by Satan in the temptation in the wilderness Matthew 4:6; but there is, in that case, no such recognition of its applicability to himself on the part of the Saviour as to justify us in the conclusion that it originally referred to him. Its quotation by the tempter is no proof that this was the original reference of the psalm, and the quotation made is one which could be applied to him in the same way as amy general premise in the Old Testament made to those who trusted in God might have been.
The most remarkable thing in the structure of the psalm is the frequent change of persons, leading some to suppose that it may have been composed with a view to its being sung by choirs in alternate responses, and Michaelis has suggested that there were probably two such choirs; the one - as in Psalms 91:1-2 - celebrating the praises of those who trusted in God; the other - as in Psalms 91:3-8 - exciting and encouraging the people to put their trust in God, and suggesting reasons why they should do it. Such a thing is, undoubtedly, possible; but the evidence that this was the intention of the author of the psalm is not clear.
Tholuck has divided the psalm, on the supposition that it was thus intended to be sung by alternate choirs, into portions arranged with that view: Psalms 91:1, the choir; Psalms 91:2, the response; Psalms 91:3-8, the choir; Psalms 91:9, the response; Psalms 91:10-13, the choir; Psalms 91:14-16, the response. This, however, is quite arbitrary, as it cannot be demonstrated to have been the original design.
This arrangement, however, suggests a good division of the psalm:
I. The general statement of the safety of those who put their trust in God, Psalms 91:1.
II. A responsive declaration of the author of the psalm, that he would make the Lord his refuge, and the Most High his habitation, Psalms 91:2.
III. A statement of the security or benefit of doing this, Psalms 91:3-8.
IV. A responsive declaration - repeated - by the author of the psalm that he would do this; that God “was” his refuge, Psalms 91:9 (part first).
V. A further statement of the benefit of this, Psalms 91:10-13.
VI. A general declaration embracing the sum of all that is said in the psalm, as coming from God himself, containing assurances of his protection to those who thus put their trust in him, and confide in him, Psalms 91:14-16.
This mode of division meets substantially all the changes of “persons” in the psalm, or arranges the different portions of it into parts belonging to the different speakers in the psalm. There is reason to believe that this was the line of thought in the mind of the psalmist, though it is not clear that this was designed to be so used in public responses in singing.