מדרש אויף איוב 19:26

“After my skin, this was struck [nikfu], and from my flesh I will view God” (Job 19:26) – Abraham said: After I circumcised myself, many proselytes came to attach themselves²Nikfu is related to mukaf, meaning attached to. to this covenant. “And from my flesh I will view God” – had I not done this, on what basis would the Holy One blessed be He have appeared to me? “The Lord appeared to him.”