Bereshis 21:2-4

Orthodox Jewish Bible

² For Sarah conceived, and bore Avraham ben in his old age, at the mo’ed (set time) of which Elohim had given promise unto him.

³ And Avraham called the shem of bno that was born unto him, whom Sarah bore to him, Yitzchak.

⁴ And Avraham circumcised bno Yitzchak at age shemonat yamim, as Elohim had commanded him.