Be merciful unto 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.
Oppresseth me - Presses hard upon me; so presses on me as always to endanger my life, and so that I feel no security anywhere.