John Gill Commentary Psalms 37:15

"Their sword shall enter into their own heart, And their bows shall be broken." — Psalms 37:15 (ASV)

Their sword shall enter into their own heart
As Saul's did into his (1 Samuel 31:4).

and their bows shall be broken;
The meaning is, that their efforts shall be fruitless, and their attempts in vain; the mischief they have contrived and designed for others shall fall upon themselves ; and therefore the saints should not be fretful and envious.