Commentaire sur La Genèse 22:19

וישב אברהם בבאר שבע AND ABRAHAM DWELT AT BEER-SHEBA — This does not mean really dwelling there but merely staying there on his way home, because he was, as a matter of fact, living at Hebron. Twelve years before the Binding of Isaac he had left Beer-Sheba and had gone to Hebron, as it is said, (21:34) ‘‘And Abraham sojourned in the land of the Philistines many days”, i.e. exceeding in number the earlier days when he had resided at Hebron — altogether 26 years, as we have explained above (21:34).

וישב אברהם, there was no need to mention that Yitzchok accompanied him. Rather it mentioned Avraham mentioned, because he was the principal.

And Avraham returned: But it is not written, Yitzchak (returned with him). Onkelos already translated that he brought him to the study hall of Shem to study Torah. And it is reasonable to say that when God finished [saying], "because you listened to My voice," he contemplated that this was the will of God - to occupy oneself with words of Torah. And even though Avraham studied with him, it is better that there be two places regarding contemplation about words of Torah, as it is found in Avodah Zarah 19a.