TT #45 · Parashas Chayei Sarah · Passuk 25:5
Avraham willed all that he owned to Yitzchak;
Torah Temimah points to Sanhedrin 91a. E-Daf · Sefaria — Sanhedrin 91a
TT lemma: כל אשר לו ליצחק.
When the children of Yishmael and the children of Keturah came to litigate… Geviha ben Pesisa cited “And he gave all that he had to Yitzchak.”
Custom (Bavli — inheritance of the Land settled by Avraham’s gift)
Avraham’s lifetime gift of the entire estate to Yitzchak, with only gifts to the other sons, settles any later claim of co-inheritance to the Land.