Exodus 32:13 Remember Abraham, Isaac, and Israel, thy servants, to whom thou swarest by thine own self, and saidst unto them, I will multiply your seed as the stars of heaven, and all this land that I have spoken of will I give unto your seed, and they shall inherit it for ever.
Moses calls on God to remember His promises. God had sworn by Himself that He would bless Abraham, Isaac, and Israel. He had promised them land and that they as a people would multiply greatly. He had promised them the land as long as time existed, forever.
God had given His Word. God will fulfill His Word. Moses knew that. You can trust that when God, who cannot lie, says something it will happen. You do not have to find a way to cover for God or excuse Him. He is the God who keeps His Word.