פירוש על בראשית 17:23

בעצם היום IN THE SELFSAME DAY — on the very day when he received the command of circumcision: by day and not by night — he was afraid neither of the heathens nor of the cynics. And he did it in broad daylight in order that his enemies and other people should not say, “If we had seen him we would never have allowed him to practise circumcision and carry out the commandment of the Omnipresent (Genesis Rabbah 47:9).

בעצם היום הזה, without any delay.

ויקח אברהם את ישמעאל בנו. Abraham took his son Ishmael, etc. Inasmuch as Ishmael had attained maturity, (he was 13 years of age) Abraham had "to take him," i.e. convince him, not merely order him to submit. The same applied to all the other members of his household who were no longer minors. Abraham was anxious that G'd's commandment to become circumcised would be accepted willingly.