זוהר בראשית — דף צג ע”ב

On the night before the circumcision, all the guests engage in Torah and each says something new. One opens with the verse “When leaders took the lead in Israel” and explains that the world endures on the covenant, and that Israel’s enemies ruled over them when it was neglected; likewise Joshua was commanded to circumcise a second time. Another cites “He sought to kill him” about Moses, whose son was not circumcised: a serpent was signaled until Zipporah circumcised her son. Another explains that Joseph showed his brothers the sign of the covenant when he said “Come near to me.” Boaz is also mentioned, who mastered his inclination, and David, of whom it says “in this I trust”; because he did not guard this sign as he should have, kingship was taken from him for a time.