When the children of Israel were living in the wilderness they were subject to many trials and afflictions, one of them being a lack of water and, in the book of Exodus, chapter 17, we read of such an incident. In answer to this God commanded Moses to strike a rock and water came out to satisfy their thirst.
In Numbers chapter 20 the Israelites are, again, without water, but on this occasion God commanded Moses not to strike the rock but to speak to it. However, in a rare display of blatant disobedience he struck the rock. For this offence he was debarred from entering the promised land (and also, no doubt, for his arrogance in stating "must we fetch you water out of this rock" - verse 10).
While we can understand God's displeasure with Moses the question remains - why did He tell Moses to strike the rock in Exodus 17 but to speak to it in Numbers 20?
It is an intriguing question and one that has perplexed many, but the answer is really very simple - because Jesus only had to die once.
Let's apply some Typology to this.
In 1st Corinthians 10 we read that when the Israelites were in the wilderness the Rock was Christ; we also know from both the Old and New Testaments that water is a symbol of spiritual cleansing- the refences are too numerous to mention here.. Moreover, the image of striking is a picture of Christ's death. In Isaiah 53 we read that Jesus was "...stricken, smitten by God, and afflicted" - verse 4. Therefore, it is not delving in the realms of fantasy to believe that the incident in Exodus 17 is a vivid picture of Christ being struck for us, and through His death we have spiritual cleansing; BUT, according to Hebrews 9 v 28, and also 10 v 12, Christ was to die "once". On the second occasion Moses should have spoken to the rock which is a picture of what we read in Romans 10 v 13 viz. "whoever calls upon the name of the Lord shall be saved".
We see, all too clearly, a profound spiritual lesson; due to Christ's death, and subsequent resurrection, the way for us to obtain spiritual cleansing, and a right standing before God, is open to all. We cannot add to that finished work. Down through the centuries huge numbers of people have sought to add to the work of Christ by their own good works and religious observances. Moreover, the Roman Catholics believe that it is possible to re-sacrifice His sacrifice which, they claim, happens during the Mass.
However, as we see from the above description of these two separate incidents, our dear Saviour only had to suffer once - the response required from us is not to add to this work, by own own efforts, but simply to call upon the Lord's name and we "will be saved".
Whoever calls upon the name of the Lord will be saved".