וַיֹּ֣אמֶר אַבְרָ֔ם הֵ֣ן לִ֔י לֹ֥א נָתַ֖תָּה זָ֑רַע וְהִנֵּ֥ה בֶן־בֵּיתִ֖י יוֹרֵ֥שׁ אֹתִֽי׃
"Certes, disait Abram, tu ne m’as pas donné de postérité, et l’enfant de ma maison sera mon héritier."
Chizkuni
וקם כל העם וישתחוו, “and the entire nation would rise and prostrated themselves;” this describes what has been written in verse 8; seeing that these two verses were very long, the Torah decided to make sure the reader would not lose track of the subject. We find that the Torah used a similar method in Genesis 15,2, when it quotes Avraham asking G-d what possible enduring gift he could give him seeing that he had no biological heir. Avraham comes back to that subject in Genesis 15,3, “reminding” Him that he has no issue. We also find such a “reminder” when Yaakov and Lavan discuss his remuneration for looking after Lavan’s flocks in Genesis 30,27. There are numerous more examples of this type in the Bible.
Or HaChaim
ויאמר אברהם…לו ישמעאל יחיה לפניך. Abraham said…. "if only Ishmael will live (a righteous life) before You." Abraham prayed that Ishmael should enjoy divine assistance to live as a righteous person. The term "to live before You" is the source for the righteous being called "alive" in our rabbinic literature. Abraham "borrowed" a phrase from Deut. 4,11 where the Torah describes the fact that the Jewish people were "alive" at that time as due to their having cleaved to G'd. Abraham saw the need to pray for this as he had observed negative character tendencies in Ishmael (who was still a minor). Had Ishmael been truly wicked at that time, Abraham, though prejudiced as his father, would have been aware of such wickedness, just as any other righteous person could perceive such things. We have explained in connection with 15,2-3 that Abraham had worried about a son of his not being worthy because G'd described his seeds as comparable to dust. At this point Abraham prayed that Ishmael would turn out to be worthy.
Siftei Chakhamim
A term indicating acceptance of terms. [Rashi is explaining that here it is] not like הן לי לא נתת זרע (15:3), which means הנה (behold).