And when all the congregation saw that Aaron had perished, all the house of Israel wept for Aaron thirty days.
29. And when all the congregation saw. This has been an error common to almost all nations and ages, but which reigned peculiarly amongst the people of Israel — to pay due honor to God’s holy servants, rather after their deaths than in their lives.
The chapter began with the funeral of Miriam, and it ends with the funeral of her brother Aaron. When death comes into a family, it often strikes double. Israel had not improved the former affliction they were under, by the death of the prophetess, and therefore, soon after, God took away their priest, to try if they would lay that to heart.
Commenting on Numbers 20:22-29
When all the congregation saw that Aaron was dead--Moses and Eleazar were the sole witnesses of his departure (Num 20:28). According to the established law, the new high priest could not have been present at the funeral of his father without contracting ceremonial defilement (Lev 21:11). But that law was dispensed with in the extraordinary circumstances.