Why, after Avraham offered the ram, does the Torah restate, "and you did not withhold your son" (this was already written in 22:12 above)?
Maharal (Chidushei Agados Vol. 1, p. 106, to Rosh Hashanah 16a): Avraham was ready and willing to offer Yitzchak, but HaSh-m withheld him from actualizing that willingness. The Torah is telling us that Avraham brought the ram in place of Yitzchak. If so, Avraham did not withhold Yitzchak; it is as if he was offered.
HaSh-m already promised Avraham that He would increase his children like the stars of the Heaven (Bereishis 15:5) and the dust of the earth (Bereishis 13:16), so what exactly is He adding in this blessing (22: 16-17)?
Ramban and Seforno: a. That, due to what Avraham just did, He now swore by His Name, (and b. that his children would capture their enemies' territory. In other words, no sin would ever cause his children to be totally wiped out, and that nothing would ever cause them to fall into the hands of their enemies, never to arise again ? Ramban). 1
Thereby rendering it unconditional, in which case it was permanent and not subject to change.
