Num 17:1 The LORD spoke to Moses, saying, “Speak to the people of Israel, and get from them staffs, one for each fathers’ house, from all their chiefs according to their fathers’ houses, twelve staffs. Write each man’s name on his staff, and write Aaron’s name on the staff of Levi. For there shall be one staff for the head of each fathers’ house. Then you shall deposit them in the tent of meeting before the testimony, where I meet with you. And the staff of the man whom I choose shall sprout. Thus I will make to cease from me the grumblings of the people of Israel, which they grumble against you.” Moses spoke to the people of Israel. And all their chiefs gave him staffs, one for each chief, according to their fathers’ houses, twelve staffs. And the staff of Aaron was among their staffs. And Moses deposited the staffs before the LORD in the tent of the testimony. On the next day Moses went into the tent of the testimony, and behold, the staff of Aaron for the house of Levi had sprouted and put forth buds and produced blossoms, and it bore ripe almonds. Then Moses brought out all the staffs from before the LORD to all the people of Israel. And they looked, and each man took his staff. And the LORD said to Moses, “Put back the staff of Aaron before the testimony, to be kept as a sign for the rebels, that you may make an end of their grumblings against me, lest they die.” Thus did Moses; as the LORD commanded him, so he did. And the people of Israel said to Moses, “Behold, we perish, we are undone, we are all undone. Everyone who comes near, who comes near to the tabernacle of the LORD, shall die. Are we all to perish?”
The rod is also a picture of God’s authority over man (Psalm 2:9, 23:4, 89:32; Isaiah 10:24, 11:4, Ezekiel 20:37). Jesus, in His divine authority, was given the title the Rod (Isaiah 11:1 and Micah 6:9). The rod was also an emblem of an apostle’s authority in the church (1 Corinthians 4:21).
Murmurers (complainers) are rarely satisfied by evidence or the resolution of one issue. Complainers are usually not issue-motivated, though they may claim to be and appear to be. More often they are heart-motivated. They sometimes murmur because they have complaining, discontented hearts. The complaining heart is demonstrated when people murmur about one issue after another, never being satisfied. So, God would give them an unmistakable answer to this matter of contention – then rid Himself of the complaints.
When Moses checked on the rods the next day, Aaron’s rod – and only the rod of Aaron – had sprouted. But God gave, as in the words of Acts 1:3, many infallible proofs, to demonstrate His approval of Aaron’s leadership. God gives us more than enough evidence; our problem is a lack of willingness to see what He has made clear. The clear choice of Aaron meant that he was God’s chosen priest and the nation was required to recognize it.
Each murmurer from the different tribes took his rod, and clearly saw that his had not budded or borne fruit, and that Aaron’s had. We can imagine Moses carefully inspecting the other rods, noting that there was nothing on them resembling a sprout, bud, or blossom. This confirmed God’s choice of Aaron, Aaron’s authority as assigned by God, and that the authority of God’s appointed high priest is fruitful. The difference between Aaron’s rod and the others could be attributed to God alone. It was a miracle that only God could do. This should have made Aaron humbler; what God did to affirm the choice of Aaron was something that had nothing to do with Aaron himself. The unfruitful rods were given back to their owners. The fruitful rod was kept before the LORD.
Aaron’s rod was to be kept in the ark of the covenant, as another example of Israel’s failure and rebellion. When God looked down from heaven into the ark, He saw emblems of Israel’s sin: The tablets of the law that they broke, the manna that they complained about, and Aaron’s rod which was the answer to their rebellion. The covering blood of sacrifice was applied to the lid covering over these reminders of Israel’s sin, so God “saw” the blood “covering” their sin, and atonement was made.
God noted that their murmuring and complaining against Aaron was actually murmuring and complaining against Himself. At the same time, there was not another direct rebellion against Aaron’s authority as the high priest in Israel after this. “The sign was efficacious; for while the spirit of rebellion manifested itself subsequently in other ways, it may safely be said that any complaint against the rights of the God-appointed priesthood ceased from this time.”
Considering the miraculous confirmation of Aaron’s priesthood, the people feared they were next to be judged and destroyed, and this was not an unreasonable fear. This kind of feverish fear doesn’t necessarily mean their hearts were changed. (Guzik)
Hearts are only changed by God in the willing hearts and minds of those who’s hearts are soft to things of God.