Sforno on Genesis 24:15/ספורנו על בראשית כ״ד:ט״ו

1טרם כלה, he had not yet finished. This is what Isaiah 65,24 had in mind when he said that G’d answers a prayer before it has been articulated.

2אשר ילדה לבתואל בן מלכה, he was not a son of Re-umah the concubine. [if the Torah had not wanted to make this point, it could simply have written Betuel, son of Nachor.]