When Moses struck the rock, who was he smiting?
He was smiting Christ. The passage identifies the spiritual rock that followed Israel as Christ, and the smitten rock prefigures the smitten Christ. This points to the cross, where Christ was smitten once for transgressions, and as a result God can pour out living water.
Les explains that when Moses took the shepherd's rod and smote the rock, he was smiting Christ. The rock was Christ, the spiritual Rock that followed them. It is the smitten Christ, pointing to the cross. Les notes that Isaiah 53 speaks of Christ being smitten for our transgressions. As a result of the work of the cross, God can pour out living water. But Christ was crucified only once, as Hebrews emphasizes: this He did once. The high priests did their work over and over, but Christ entered in once. So the smitten rock typifies the once-for-all sacrifice of Christ, and the water from the rock points to the living water made available through the cross.