Bereshis 21:3-5

Orthodox Jewish Bible

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.

⁵ And Avraham was a hundred years old, when bno Yitzchak was born unto him.