Genesis 17:23 BBE

²¹  But my agreement will be with Isaac, to whom Sarah will give birth a year from this time.

²²  And having said these words, God went up from Abraham.

²³  And Abraham took Ishmael, his son, and all whose birth had taken place in his house, and all his servants whom he had made his for a price, every male of his house, and on that very day he gave them circumcision in the flesh of their private parts as God had said to him.

²⁴  Abraham was ninety-nine years old when he underwent circumcision.

²⁵  And Ishmael, his son, was thirteen years old when he underwent circumcision.