Parashas Chayei Sarah · Passuk 25:9
His sons Yitzchak and Yishmael buried him in the cave of Machpelah, in the field of Efron son of Tzochar the Hittite, facing Mamre,
Torah Temimah points to Bava Basra 16b. E-Daf · Sefaria — Bava Basra 16b
TT lemma: יצחק וישמעאל.
Rabbi Yochanan said: Yishmael repented in the lifetime of his father, as it is said “And Yitzchak and Yishmael his sons buried him”; from the fact that [the verse] placed [Yitzchak] first, [we learn that Yishmael] accorded him honor.
Custom (Bavli — Yishmael’s repentance during Avraham’s lifetime)
Yishmael repented while Avraham was still alive; the verse’s placing of Yitzchak before Yishmael at the burial demonstrates that honor and the prior teshuvah.