Numbers 17:3Meaning & Commentary from the Church Fathers

The stature of the priesthood is truly noble. Consequently, when certain malevolent individuals confronted Aaron in an effort to strip him of his role and questioned his esteem, the humble Moses sought to demonstrate through action that Aaron was not elevated to this sacred position merely because he was his brother and relative, but rather that the priestly office had been bestowed upon him in accordance with God's will. To illustrate this, Moses instructed that a staff be presented from each tribe, including one for Aaron.

To provide the people with strong confirmation that the grace of God’s priesthood is bestowed upon those chosen for it, Moses gathers the staffs from the leaders of each tribe. He inscribes the name of each leader on their respective staff, including Aaron's priestly staff, and presents them in the temple. In this way, the subsequent law conveys that the priesthood is a sacred calling rather than a human entitlement. By placing the staffs, marked by the names of their donators, upon the altar, Moses seeks to highlight the staff that would be set apart through a divine miracle as a testament to the heavenly ordination.