Rashi on Deuteronomy 11:21/רש"י על דברים י״א:כ״א

1למען ירבו ימיכם וימי בניכם IN ORDER THAT YOUR DAYS MAY BE INCREASED AND THE DAYS OF YOUR CHILDREN — We may learn from this that if you do so, then they will be increased, but if not, they will not be increased, for the statements of the Torah may be expounded so as to derive from the negative the positive, and from the positive, the negative (Sifrei Devarim 46).

2לתת להם [THE LAND WHICH THE LORD SWARE UNTO YOUR FATHERS] TO GIVE TO THEM — It is not written here “to give to you”, but “to give to them”. From this we are able to derive that the tenet of the “Resurrection of the Dead” is of Biblical origin (more lit., is from the Torah) (Sifrei Devarim 47:2).