The table below presents an aligned extract of verses or verselets in Dt11-21b, (Gn17-08 Gn26-03 Gn28-13. Both verses/verselets discuss the inheritance of Israel. The alignment justifies the Rashi comment that: All three Patriarchs were promised the land of Israel would be given to them and to their descendants. But in Dt11-21 God refers to the land promised to them. Hence the emphasis that not only will the Jewish people inherit Israel but the Patriarchs themselves will also so inherit (upon resurrection).

Verse	Text of Verse	Rashi comment
Dt11-21b	That your days may be multiplied, and the days of your children, in the land which the Lord swore to your fathers to give to them, as the days of heaven upon the earth.	All three Patriarchs were promised the land of Israel would be given to them and to their descendants. But in Dt11-21 God refers to the land promised to them. Hence the emphasis that not only will the Jewish people inherit Israel but the Patriarchs themselves will also so inherit (upon resurrection).
Gn17-08, Gn26-03, Gn28-13	[summary paraphrase of all 3 verses] And I [God] will give to you and to your descendants ....the land of Canaan

Advanced Rashi: Another approach to this Rashi is through the format rule. If you inspect all three promises to the Patriarchs you will see a repetition of the repeating keyword to. The repetition of to in to you and to your descendants creates a bullet like effect emphasizing that both the Patriarchs themselves as well as their descendants will inherit Israel.

Note, traditional Rashi=ists would learn this Rashi from the emphasized phrase to you. But you by itself could mean the plural you and refer to your nation. However, Rashi is preferably learned by the emphasis indicated by the bullets or by the aligned contrast which emphasizes both you and your descendants.