Af and Chemah: Dark Angels of Destruction
R. Judah b. Bizna lectured: When Moses was lax in the performance of circumcision, Af and Hemah came and swallowed him up, leaving nought but his legs. Thereupon immediately Zipporah 'took a sharp stone and cut off the foreskin of her son'; straightway he [they?] let him alone. In that moment Moses desired to slay them, as it is written, "Cease from Af and forsake Hemah" (Deut. 9:19) (Nedarim 32a) Zal g'mor - To learn more consult the Encyclopedia of Jewish Myth, Magic, and Mysticism: http://www.amazon.com/Encyclopedia-Jewish-Myth-Magic-Mysticism/dp/0738709050
1. Trans. from the Soncino Talmud.