Psalms 42:8

[Yet] the Lord will command his lovingkindness in the
daytime
Which is a tender affection in God towards his people, springs from his sovereign will and pleasure, is from everlasting, is ever the same, never removes from them, and is better than life; the effects of which are all spiritual blessings, grace, and glory: and this the Lord "commands" when he sends it forth with power, makes a clear manifestation and home application of it to them; when he commands his covenant, or bestows covenant blessings on them; when he commands his strength, or gives them strength to bear up under afflictions; when he commands deliverances for Jacob, or works salvation for them; and when he commands blessings temporal and spiritual on them, especially life for evermore: see ( Psalms 111:9 ) ( 68:29 ) ( Psalms 44:4 ) ( 133:3 ) ; and this is done in "the daytime"; either, as some interpret it, in a fit and seasonable time, in God's appointed time, who has his set time to favour his people, and show his lovingkindness to them; or openly and publicly, so as themselves and others may see the salvation of the Lord; or continually; for mercy, goodness, and lovingkindness, follow them all the days of their lives; yea, are from everlasting to everlasting: and these words may be read either in the past tense, as some do, "yet the Lord hath commanded" ^F13 and so respect what had been, and relate to the former experiences and manifestations of the love of God, with which the psalmist encourages himself under his present afflictions; or in the future, as in our version; and so they are an expression of faith as to what would be hereafter, that the Lord would appear again, and show him his face and favour;

and in the night his song [shall be] with me;
signifying hereby, that he strongly believed he should have occasion of singing praise to God in the night season, though he was now in such mournful circumstances: he calls it "his song"; that is, the Lord's song; because the matter of it are his lovingkindness, and the blessings springing from it; because the Lord himself is the subject of it; his perfections, his works, his salvation and glory; and because he gives songs in the night, and puts them into the mouths of his people; see ( Isaiah 12:2 ) ( Job 35:10 ) ; and the psalmist says it would be with him, in his heart, and in his mouth, and be his constant companion wherever he was, lying down, or rising up; and that "in the night"; either figuratively understood of affliction and distress, out of which he would be delivered, and so be compassed about with songs of deliverance; or literally, it being a time of leisure to call to mind the salvation and mercies of the day, and be thankful for them; see ( Psalms 77:6 ) ( 119:62 ) ( Acts 16:25 ) ;

[and] my prayer unto the God of my life:
natural, spiritual, and eternal; being the author, giver, and preserver of each; and this is no inconsiderable mercy, to have such a God to pray unto in a time of distress; as well as in a time of salvation, to go to, and make known requests with thanksgiving; which seems to be intended here, since it is joined with a song. Prayer and praise go together, the object of which are not lifeless idols, that cannot save; but the living God, who is a God hearing and answering prayer, and does not despise the prayer of the destitute. The prayer of the psalmist follows.