1)
Why was Avraham adamant that Yitzchak not go there?
1.
Malbim: 'HaSh-m took me and my seed from there' (like the next verse says). If Yitzchak returns there, it is as if I return there.
2.
Ha'amek Davar: Yitzchak was considered like a Korban Olah (due to the Akeidah), so he could not go to Chutz la'Aretz. 1
1
Rashi (26:2) writes that Yitzchak thought to go to Egypt when there was a famine. Had Avraham not told him they he may not leave Eretz Yisrael?! (PF)
