In this parsha, Moses gives his final blessing to the bnei Yisrael. The Ohr Hachaim points out that Moses had suffered for forty years from his cantankerous people. Moses had only one wish, to be allowed into the Holy Land, but he was denied this fervent wish because of the Israelites' sins (Deuteronomy 4:21). One would think that before his death, he would express his anger to them.
But what happened was just the reverse. Virtually with his last breath, he blessed them wholeheartedly. Moses did not carry any resentments, in spite of his terrible disappointment that his prayers were denied, and he blessed the people who were responsible for his not entering the Holy Land.
We say Moshe Rabeinu, Moses is our teacher. On the last day of his life, he taught us not to harbor resentments, and to bless those who have offended us.