וְאַבְרָ֕ם בֶּן־שְׁמֹנִ֥ים שָׁנָ֖ה וְשֵׁ֣שׁ שָׁנִ֑ים בְּלֶֽדֶת־הָגָ֥ר אֶת־יִשְׁמָעֵ֖אל לְאַבְרָֽם׃ (ס)
하갈이 아브람에게 이스마엘을 낳을 때에 아브람이 팔십육 세이었더라
Rashbam
ואלה שני חיי ישמעאל, our sages, both in Megillah 17 and Yevamot 64 deal with the reason why the Torah thought it necessary to inform us of Ishmael’s age at his death. According to the plain meaning of the text, the Torah wrote this out of respect for Avraham. Seeing that the Torah had told us of Avraham’s age being 86 when he fathered Ishmael, and it also told us of Ishmael being 13 years of age when he underwent circumcision, it now concludes by telling us Ishmael’s age at his death.