Or HaChaim on Deuteronomy 4:21/אור החיים על דברים ד׳:כ״א

1 וה׳ התאנף בי על דבריכם, "G'd was angry at me on account of you." Moses repeated this once more, not content with what he had said already in 1,37. He also repeated twice: "not to let me cross the Jordan and not to let me come to the good land." He meant that he suffered not only from the decree of having to die in the desert but from another decree i.e. that even his bones would not be buried in ארץ ישראל although he had made sure that both Joseph's remains and the remains of the brothers would be buried in holy soil (compare Jerusalem Talmud Sotah 1,10). The first time he mentioned the word לבלתי he referred to his not entering the Holy Land while alive, whereas the second time he mentioned that word he referred to not even being brought to burial there. Moses repeats the same theme in another form when he says in verse 22: "I am going to die in this land and I will not cross the Jordan." He means that he will neither cross the Jordan alive nor dead. He contrasts this with the Jewish people, his charges, whom he congratulates by saying: "you will cross and inherit the land." The form of address is what is known as לא זו אף זו, i.e. "not only will you cross the Jordan but you will even take possession of that land."

2Devarim Rabbah approaches the meaning of the words על דבריכם by means of a parable. A person had lost some money in a dark place. He said to himself that if he were to ask people to light up the area for him so that he could retrieve his money no one would pay any attention to him. What did he do? He threw a gold coin amongst the people present and started yelling that he had a single gold coin and now he lost it. He begged people to provide some light so that he could retrieve his coin. The people brought a lantern; once he had retrieved his coin he asked them to wait a little longer until he could find the rest of his money. Eventually, he did retrieve all his money. Moses, or G'd if you will, found himself in a similar situation. Once G'd would make the effort to resurrect Moses, He would wait a little longer to resurrect his generation with him at the same time. After all, Moses had taken them out of Egypt (so that they could be considered his "money"), and it would only be fair that he would bring them to their destination, the land of Israel. Thus far the Midrash. This is an illustration of the word על דבריכם, i.e. if it were not for G'd wanting to bring the Israelites of the generation of the Exodus to the Hereafter eventually, there would have been no need for Moses to be buried on the East Bank of the Jordan.