Psalms 42:8 - Matthew Poole's English Annotations on the Holy Bible

Will command i.e. will effectually procure or confer upon me, as this verb is used, Leviticus 25:21 Psalms 7:6, &c. The verb is future, but some render it by the time past, the Lord hath commanded; making this rehearsal of his former experiences of God's goodness his argument to support himself, and to prevail with God in prayer; which may seem to suit best with the foregoing and following verses. But we must remember that David's hopes and fears were strangely mixed, and his expressions of them are commonly interwoven in the same Psalm, and sometimes in one and the same verse, as it is here, Psalms 42:5,11. And therefore there is no necessity of departing from the proper signification of the verb. His loving-kindness, i.e. his blessings, the effects of his loving-kindness, which God is oft said to command, as Deuteronomy 28:8 Psalms 133:3. And in the night; both day and night, i.e. continually. His song shall be with me, i.e. I shall have constant matter of singing and praising God for his loving-kindness. My prayer shall be unto the God; and therefore I will boldly and believingly direct my prayers to him, of whose readiness to hear and help me I have had such ample experience. The God of my life; the giver and preserver of my life from time to time.