Albert Barnes Commentary Deuteronomy 34:5

"So Moses the servant of Jehovah died there in the land of Moab, according to the word of Jehovah." — Deuteronomy 34:5 (ASV)

According to the word of the Lord - It denotes that Moses died, not because his vital powers were exhausted, but by the sentence of God, and as a punishment for his sin. Compare (Deuteronomy 32:51).