Preserve me, O God: for in thee do I put my trust - On the mode of interpretation which I have hinted at above, I consider this a prayer of the man Christ Jesus on his entering on his great atoning work, particularly his passion in the garden of Gethsemane. In that passion, Jesus Christ most evidently speaks as man; and with the strictest propriety, as it was the manhood, not the Godhead, that was engaged in the suffering.
שמרני shomreni, keep me - preserve, sustain, this feeble humanity, now about to bear the load of that punishment due to the whole of the human race. For in thee, חסיתי chasithi, have I hoped. No human fortitude, or animal courage, can avail in my circumstances. These are no common sufferings; they are not of a natural kind; they are not proportioned to the strength of a human body, or the energy of a human spirit; and my immaculate humanity, which is subjected to these sufferings, must be dissolved by them, if not upheld by thee, the strong God. It is worthy of remark, that our Lord here uses the term, אל El, which signifies the strong God, an expression remarkably suited to the frailty of that human nature, which was now entering upon its vicarious sufferings. It will be seen with what admirable propriety the Messiah varies the appellations of the Divine Being in this address; a circumstance which no translation without paraphrase can express.
Preserve me, O God - Keep me; guard me; save me. This language implies that there was imminent danger of some kind - perhaps, as the subsequent part of the psalm would seem to indicate, danger of death. See Psalm 16:8-10. The idea here is, that God was able to preserve him from the impending danger, and that he might hope he would do it.
For in thee do I put my trust - That is, my hope is in thee. He had no other reliance than God; but he had confidence in him - he felt assured that there was safety there.