And the days of Israel drew near to die. And he called to his son, to Joseph, and said to him, If now I have found favour before thee, put thy hand on the place of my circumcision, and deal with me in goodness and truth, That thou wilt not bury me in Mizraim,
Why Jacob Made Joseph Swear by the Mark of Circumcision
Targum Pseudo-Jonathan on Genesis 47:29