LXX Gen 17:25

Ἱσμαὴλ δὲ ὁ υἱὸς αὐτοῦ ἐτῶν δέκα τριῶν ἦν, ἡνίκα περιτὴν σάρκα τῆς ἀκροβυστίας αὐτοῦ.

and his son Ishmael was thirteen;