Therefore, Avraham said to Hashem (Bereishis 17:18), “If only Yishmael could live with awe in Your Presence,”
After Hashem told Avraham that he would have a son Yitzchok, Avraham asked that Yishmael should also be able to fear Hashem and serve Him. The question is: Why is it specifically when Avraham has a Bris Milah he discusses getting Yishmael to fear Hashem, wasn’t he trying to instill the fear of Hashem in Yishmael the entire time?
Because once his name was changed and he was called “אַבְרָהָם-Avraham” with a ה', through which he gained the ability to draw down revelations of Hashem into the level of Malchus, because he was given the mitzvah of Milah, he was able to elevate sparks of Holiness like a candle becomes absorbed before a torch, that these sparks become included in the level of Malchus.
Because of Avraham’s new-found ability to elevate Sparks of Holiness that were trapped in physicality, he now wanted to try again to elevate Yishmael out of unholiness and instill the fear of Hashem in him.
As it is written (Bereishis 12:5), “Avram took his wife Sarai and his nephew Lot, and all their possessions that they owned, and the souls (i.e., people) that they ‘made’ (i.e., purchased) in Charan, and they left to travel to the land of Kanaan, and they arrived in the land of Kanaan.”
