What does the Pasuk mean when it writes that Avraham took Yishmael and the other men of his household?
Ramban: Bearing in mind that Yishmael was already thirteen, Avraham took him with words - he convinced him (and the other members of him household) verbally that this was the right thing to do, because he wanted them to perform the Mitzvos of Hashem willingly, not by force.
What is the significance of the phrase "be'Etzem ha'Yom ha'Zeh"?
Rashi #1 and Seforno: He performed the Mitzvah immediately, on the same day that he instructed.
Rashi #2: He was not afraid of those 1 who would try to stop him from fulfilling Hashem's command. That is why the Torah adds that he performed the Mitzvah by day, 2 so that nobody would be able to subsequently claim that, had they known about it, they would not have let him do it.
Moshav Zekenim (on Bereishis 18:1): Even though he did other Mitzvos early, here he waited until midday, for publicity.
Why does the Torah see fit to add "like Hashem spoke to him", which seems to add nothing to the context?
Ramban #1: It is telling us that speaking to them softly (as he just explained) was itself by Divine command.
Ramban #2: It teaches us that he did not delay carrying out Hashem's command, thereby demonstrating his Midas ha'Zerizus.
Ramban #3: The Pasuk is telling us that Avraham fulfilled the command of Pasuk 17 that only someone who is himself circumcised may circumcise others. 1