New Defender's Study Bible Notes
20:8 Take the rod. This was not the rod of judgment, with which Moses had smitten the rock almost forty years before. Water from that rock had followed them as a perennially flowing stream through all their wilderness wanderings. The rod mentioned here was Aaron’s rod that budded (Numbers 17:10; 20:9), implying resurrection instead of judgment.
20:8 speak ye unto the rock. This rock was a high craggy rock (in Hebrew cela), in contrast to the small rock (in Hebrew tsur), which had been smitten before (Exodus 17:6).