1)
Why did Moshe mention the Avos, who were long dead?
1.
Rashi: This teaches us that, when Yisrael suffer punishments, the Avos suffer together with them.
2.
Ibn Ezra: "ve'la'Avoseinu" refers to the previous generation who died in the desert.
3.
Oznayim laa'Torah: Refer to 20:14:3:1*. And he added "ve'la'Avoseinu", to impress upon Edom the cruelty of the Egyptians, who, following the death of Yosef, subjugated his brothers whom Par'oh had invited as a token of thanks to Yosef who had saved the country, and filled his coffers with.
