Parshat Hayyei Sarah
In 25:8 the passuk tells us, "וימת אברהם בשיבה טובה זקן ושבע" - and Avraham died at an old age, old and satisfied.
This is a very unusual term. Usually it just says "so and so died". Here it tells us he was old and satisfied... Why all the extra descriptions?
Rashi adds that Avraham died happy because he knew Yishmael had done repentance, as was indicated by his giving respect to Yitzchak and letting him go first.
Just because he let Yitzchak goes first means everything is ok? Maybe he is still a murderer or idol worshiper? Maybe he simply came to terms with Yitzchak being the more prominent son?
Nobody wants to see their children fighting with each other and involved in a lifetime bitter feud. People want to see their children get along with each other. Interacting with each other. Respecting each other.
That image alone, of seeing Yishmael abandon his bitterness towards Yitzchak, was enough to give Avraham the comfort, the nachas he always wanted, and that allowed Avraham to die peacefully and satisfied.
Because he finally achieved this level of satisfaction right before his death, that is why the passuk tells us that he died old and satisfied.
This teaches us a lesson how important it is to maintain peace in the family. Avraham's whole life it disturbed him and took away from his peace that his children fought. Only right before he died did he achieve satisfaction because his kids make peace, and that satisfaction is important enough that the Torah mentions it.