Aaron’s rod was one of twelve rods placed in the Tent of the Testimony, each representing a tribe and bearing its prince’s name. Aaron’s rod miraculously budded, blossomed, and produced almonds, displaying all three stages of plant life at once.
The sign confirmed Aaron’s divine appointment and priestly right after the rebellion against Moses and Aaron. It was kept before the testimony as a lasting token of God’s will; Hebrews mentions it in connection with the Holy of Holies and the ark.
The rod was preserved in the sanctuary after the people accepted the sign as final.