Comentario citado sobre Deuteronómio 29:9

ויקרא משה אל כל ישראל, Moses called out to the entire Jewish people, etc. Even though Moses had been addressing the whole Jewish people up until now also, he gathered the women and the children as well as the proselytes to prepare them for renewed acceptance of the covenant which is the subject of Parshat Nitzavim.

AND MOSES WENT. When Moses concluded his words, all who stood before him, and the young children, and the women returned to their own tents. It was not necessary for Scripture to mention this [that they returned to their tents], for it already stated, Ye are standing this day all of you before the Eternal your G-d;¹Above, 29:9. that thou shouldest enter into the covenant of the Eternal thy G-d,²Ibid., Verse 11. and [it is self-understood that] after having entered the covenant they would go away from him [Moses]. And so Scripture now states that Moses went from the camp of the Levites to the camp of the Israelites in order to show them honor, like someone who wishes to take leave of his friend and comes to ask permission of him.

וירא אליו ה' באלוני ממרא, because this was where Avraham had circumcised himself at that time. His whole household had been circumcised with him at the time. This is where G’d manifested Himself as a sign that He stood by the covenant, similar to the verse at the beginning of Deuteronomy 29,9-11, commencing with the words אתם נצבים היום, and to Kings II 23,3 ויכרות לפני ה'. He appeared to Avraham seeing he was the individual most deserving to be the recipient of such a vision. We have a similar occurrence in Exodus 4,24 ויפגשהו ה', where G’d “met” with Moses without delivering an oral message. At that time G’d’s purpose was to ensure that Moses would circumcise his son, to maintain the covenant which was to be an eternal covenant with the descendants of Avraham as spelled out in Genesis 17,11-12. Perhaps this is the reason why a chair is prepared at the occasion of the circumcision (Pirkey de Rabbi Eliezer 29, as well as Zohar Bereshit 13,10) This chair alludes to the fact that hopefully, the presence of G’d will attend this marking of the sign of the covenant by a new member of the Jewish people.