For innumerable evils have compassed me about - Have surrounded me, or have beset me on every side. The evils here referred to, understood as being those which came upon the Messiah, were sorrows that came upon him in consequence of his undertaking to do what could not be done by sacrifices and offerings Psalms 40:6; that is, his undertaking to save men by his own “obedience unto death.” The time referred to here, I apprehend, is that when the full effects of his having assumed the sins of the world to make expiation for them came upon him; when he was about to endure the agonies of Gethsemane and Calvary.
Mine iniquities have taken hold upon me - On this passage, as constituting one of the main objections, and the strongest objection, to the application of the psalm to the Messiah, and on the way in which such objection may be met, see introduction to this psalm (3b).
So that I am not able to look up - This is not the exact idea of the Hebrew word. That is simply, I am not able to see; and it refers to the dimness or failure of sight caused by distress, weakness, or old age. 1 Samuel 3:2; 1 Samuel 4:15; 1 Kings 14:4; compare Psalms 6:7. The idea here is, not that he was unable to look up, but that the calamities which came upon him were so heavy and severe as to make his sight dim, or to deprive him of vision. Either by weeping, or by the mere pressure of suffering, he was so affected as almost to be deprived of the power of seeing.
They are more than the hairs of mine head - That is, the sorrows that come upon me in connection with sin. The idea is that they were innumerable - the hairs of the head, or the sands on the seashore; being employed in the Scriptures to denote what cannot be numbered. See Psalms 69:4. Compare Genesis 22:17; Genesis 32:12; Joshua 11:4; 2 Samuel 17:11.
Therefore my heart faileth me - Margin, as in Hebrew: “forsaketh.” The idea is that he sank under these sufferings; he could not sustain them.