Why does it say "va'Ya'amideha l'Yakov l'Chok"?
Radak: The Shevu'ah was for the special seed of Yitzchak - Yakov, and not for Esav. Yitzchak told Yakov "va'Yiten Lecha Es Birkas Avraham" (Bereishis 28:4).
Malbim: For Yakov He established the Bris to be a fixed statute, as if it is a law that must be fulfilled due to itself.
Why does it say "l'Yisrael Bris Olam"?
Malbim: Yisrael are a higher level than Yakov. For Yisrael it is a Bris via which the world is sustained. When Yisrael is elevated above nature, like the name Yisrael demonstrates 1 , then the Bris is for a difficult conduct via Hashgachah, unlike the first Bris Olam of natural conduct. He tied the two together, so if one Bris is nullified, also the latter will be - "Im Lo Brisi Yomam?; Gam Zera Yakov? Em'as" (Yirmeyah 33:25-26).
Bereishis 32:29: "Ki Sarisa Im Elohim v'Im Anashim va'Tuchal" (PF).
