Numbers 17:3
And thou shalt write Aaron’s name upon the rod of Levi: for one rod shall be for the head of the house of their fathers. And thou shalt write Aaron’s name upon the rod of Levi: for one rod shall be for the head of the house of their fathers.
The instruction was that Aaron's name should be inscribed on the rod for Levi, so that one rod stood for the head of each father's house and each tribe had its own rod. Levi was thus represented by a single rod bearing Aaron's name as the head of its ancestral house.
Those named rods were to be laid up before God, before the testimony, as a divine test to make known whom He had chosen. The sign would be that the rod which blossomed would identify God's choice. When Aaron's rod blossomed, it established that God had appointed Aaron's house and family to the priesthood. That miracle settled the dispute and rebellion over the priesthood. The rod was then preserved as a lasting sign and witness to later generations to put an end to complaints.