Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
CUT'TINGS IN THE FLESH. This repulsive practice, common among idolaters, ancient and modern, originates in the notion that pain and blood please the angry deity. Cutting with a knife also formed a part of a funeral ceremony. It would seem that the Syrians were particularly addicted to the custom; accordingly, the Israelites were strongly forbidden thus to mutilate themselves. Comp. Lev 19:28; Deut 14:1; 1 Kgs 18:28; Jer 16:6.