"23 And the Lord said to Moses and Aaron at Mount Hor, on the border of the land of Edom, 24 “Let Aaron be gathered to his people, for he shall not enter the land that I have given to the people of Israel, because you rebelled against my command at the waters of Meribah. 25 Take Aaron and Eleazar his son and bring them up to Mount Hor. 26 And strip Aaron of his garments and put them on Eleazar his son. And Aaron shall be gathered to his people and shall die there.” 27 Moses did as the Lord commanded. And they went up Mount Hor in the sight of all the congregation. 28 And Moses stripped Aaron of his garments and put them on Eleazar his son. And Aaron died there on the top of the mountain. Then Moses and Eleazar came down from the mountain. 29 And when all the congregation saw that Aaron had perished, all the house of Israel wept for Aaron thirty days."
Numbers 20:23-29
The last verses of the chapter record the death of Aaron. We should not miss the significant fact that the chapter which ends with the record of the death of Aaron began with that of the death of Miriam. What must this have meant to Moses, in terms of bleak desolation and loneliness, Miriam's death took? It seems likely, therefore, that that year saw the double bereavement of God's appointed leader, and it says something to us about Moses' stature that he should have continued without interruption in his divinely ordained work even in such a context of sorrow and grief. The reason for Aaron's death at this point is emphasised again in 24 (cf 12,13), but there is almost a gentleness and certainly a solemn dignity in the Lord's words about his being gathered unto his people. And, withal, there is a beautiful sense of continuity in Aaron's son Eleazer being invested with the priestly garments and authority. As we say, 'God buries His workers, and carries on His work'. There was to be no interruption of the divine provision for His people. They were not to be without a high priest. And surely this serves to remind us of the wonderful words in Hebrews 8:23, 24 about the imperfection of the Levitical priesthood: 'They truly were many priests, because they were not suffered to continue by reason of death; but this man, because he continueth ever, hath an unchangeable priesthood.'