And the LORD spake unto Moses, saying, Take the rod, and gather thou the assembly together, thou, and Aaron thy brother, and speak ye unto the rock before their eyes; and it shall give forth his water, and thou shalt bring forth to them water out of the rock: so thou shalt give the congregation and their beasts drink (Numbers 20:7,8).
Almost twenty years earlier, in very similar circumstances, the Israelites were threatening to kill Moses for lack of water. God had told him to smite the rock instead. A spring of water erupted which had then supplied their needs through all those years. But now, somehow, that source had ceased, and once again the people started complaining. They had been taking the miraculous water supply for granted, and it was needful that they should realize afresh the source of their blessings. Therefore, although the water was withheld for a time, God had merely desired that they come to Him and ask once again. Instead, they grumbled, forgetting all Gods previous gifts.
So God told Moses to do the asking for them, as they were watching. This time, however, Moses would not need his Egyptian rod of judgment. Instead, God told him to take Aarons rod from before the LORD (v.9), where it had been laid up (Numbers 17:6,7). It was appropriate to remind them that Moses and Aaron were still their leaders, and God was still able to supply their needs.
Moses did take the rod and did speak to the rock, and the water did flow once again. But this time Moses himself failed. In his anger, he berated the people and then smote the rock, even taking credit for supplying the water, and failing to direct the gratitude of the people to the Lord as God had desired.
Moses, therefore, never was allowed to enter Canaan. It is not pleasing to God when one of His servants, no matter how eminent he may be, usurps the credit and praise which should belong only to the Lord. HMM