'Slashes' in the Bible

Priests must not have a bald spot shaved on their head, they must not shave the corner of their beard, and they must not cut slashes in their body.

“His arrows surround me.He pierces my kidneys (vital organs) without mercy;He pours out my gall on the ground.

For every head is [shaven] bald and every beard cut off; there are cuts (slashes) on all the hands and sackcloth on the loins [all expressions of mourning].