John Gill Commentary Psalms 38:4

"For mine iniquities are gone over my head: As a heavy burden they are too heavy for me." — Psalms 38:4 (ASV)

For mine iniquities are gone over mine head
Like an inundation of waters, as the waves and billows of the sea; for the waters to come up to the neck or chin shows great danger; but when they go over the head the case is desperate, and a person is sinking and drowning; compare with this (Psalms 69:1Psalms 69:2) ; the simile may denote both the number and weight of sins, and also signifies the overwhelming distress the psalmist was in, under a view of them;

as an heavy burden, they are too heavy for me ;
the guilt of sin upon the conscience, without a view of pardon, lies heavy indeed, and makes a man a burden to himself, as it did Job, (Job 7:20Job 7:21) ; yea, sin is not only grieving and afflicting to pardoned ones, and who know they are pardoned, but it is a burden to them under which they groan; nor is it possible for any so to bear it as to satisfy and make atonement for it; none but Christ could ever do this, and he has done it; nor is there any relief for burdened souls, but by looking to a sin bearing and sin atoning Saviour, and by casting the burden upon him, who invites them to him for rest.