en_tn_condensed/psa/109/018.md

He clothed himself with cursing as his garment

David speaks of the wicked person's behavior as if it were his clothing. This probably means he cursed people very often. Alternate translation: “Curses were like his clothing” or “He cursed people all the time” (See: rc://en/ta/man/jit/figs-metaphor)

his curse came into his body like water, like oil into his bones

Possible meanings are: 1) He spoke curses so often that they became a part of his identity. "the curses that he speaks are part of who he is" or 2) David prays that the wicked man will experience his own curses. Alternate translation: “may his curse come into his body like water, like oil into his bones” (See: rc://en/ta/man/jit/figs-simile)

like oil into his bones

People believed that oil rubbed on the skin went into the bones.