2 Samuel 23:21

And he slew an Egyptian, a goodly man: and the Egyptian had a spear in his hand; but he went down to him with a staff, and plucked the spear out of the Egyptian’s hand, and slew him with his own spear.

Cross-reference

1 Samuel 17:51 shows David killing Goliath with his own sword, mirroring Benaiah's use of the Egyptian's spear.

1 Chronicles 11:23 gives the parallel account of Benaiah killing the Egyptian giant with his own spear.