Rashi on Genesis 25:9/רש"י על בראשית כ״ה:ט׳

1יצחק וישמעאל ISAAC AND ISHMAEL — From this we gather that Ishmael repented of his evil ways (cf.Bava Batra 16b) and yielded the precedence to Isaac. This is what is meant by the “good old age” mentioned in connection with Abraham (Genesis Rabbah 38:12).