http://revach.net/article.php?id=4158

Section:  Avodah   Category: Chanoch L'Naar
Parshas Chayei Sara: Rav Moshe Feinstein - A Son Is Everything!
The pasuk says, "VaHashem Beirach Es Avrohom BaKol", Hashem blessed Avrohom with everything  (Chayei Sara 24:1).  Rashi says that the word "BaKol" is gematria "Ben" a son, meaning Hashem blessed Avrohom with Yitzchok.  Rav Moshe Feinstein asks, why does the Torah tell us this with a Remez and not directly.

He answers that the gemara in Bava Basra (17a) says that the Bakol the Avrohom received meant every possible good in the world.  No possible pleasure eluded him.  Yet Avrohom knew that without a son to carry on his legacy, his mitzvos, his piety, and even his pleasures did not amount to anything.  When the Torah tells us that Avrohom had it all, BaKol, included in that is the son that would follow in his way and make his life's work meaningful.