Albert Barnes Commentary Psalms 56:1

"Be merciful unto me, O God; for man would swallow me up: All the day long he fighting oppresseth me." — Psalms 56:1 (ASV)

Be merciful to me, O God - See the notes at (Psalms 51:1).

For man would swallow me up - The word used here means properly to breathe hard; to pant; to blow hard; and then, to pant after, to yawn after with open mouth. The idea is that people came upon him everywhere with open mouth, as if they would swallow him down whole.

He found no friend in man—in any man. Everywhere his life was sought. There was no “man,” wherever he might go, on whom he could rely or whom he could trust; and his only refuge, therefore, was in God.

He fighting daily - Constantly, without intermission. That is, all people seemed to be at war with him and to pursue him always.

Oppresses me - Presses hard upon me; he presses on me in such a way as to always endanger my life, so that I feel no security anywhere.