Why did Amalek not attack Yisrael on their way down to Egypt, when they numbered only seventy souls?
Da'as Zekeinim mi'Ba'alei Tosfos: Because he realized that, once Yitzchak died, the fulfillment of the prophecy "va'Avadum ve'Inu osam Arba Me'os Shanah" would have fallen upon Ya'akov and his children and upon Eisav and his children, in which case, if he were to kill Y'akov and his descendents, it would fall upon him alone to fulfill. So he waited until Ya'akov's children had 'paid the debt' before attacking. 1
Here it says that Bnei Yisrael tested Hashem. In Devarim (34:7), it says that Hashem tested Shevet Levi at Masah!
Rashi (Devarim 34:7): Levi's test was not to complain with the other complainers.