Numbers 33:39

And Aaron was an hundred and twenty and three years old when he died in mount Hor.

Aaron died on Mount Hor. He was a hundred and twenty-three years old when he died there. His death followed Israel's stay at Kadesh on the very borders of Canaan. That was where Miriam died and was buried and where unbelief kept the people from entering, where Israel murmured for water and Moses was provoked to speak rashly with his mouth and take glory to himself instead of giving glory to God, and where Edom heartlessly refused Israel passage through its land.

His burial was carried out by God's command and was witnessed only by Moses and Eleazar, and his grave was hidden from Israel. His death brought thirty days of mourning for Israel. It reminded Moses that his own death was near. Aaron served as high priest from his anointing until his death, since the fifty-year age limit applied to manual sanctuary service and not to official service or sacred rites. Because the priest's office continued throughout his life, it illustrates why Christ's priesthood has no end, unlike the priesthood of mortal priests.