Rashi on Genesis 24:1/רש"י על בראשית כ״ד:א׳

1ברך את אברהם בכל [THE LORD HAD] BLESSED ABRAHAM IN ALL THINGS — The numerical value of the word בכל is equal to that of בן (a son) — suggesting that God had blessed Abraham with a son and since he had a son he had to find him a wife.