If you re-read Numbers 20:6–11, you’ll see that Moses and Aaron did not do as the Lord commanded them to do. He asked them to speak to the rock and told them that it would bring forth water. Instead, Moses and Aaron decided to strike the rock for water, which was a method of obtaining water that had previously been successful for them (Ex. 17:5–7). In other words, they decided to ignore the Lord’s request and go with what had worked before, which demonstrated a lack of faith (Num. 20:12) and, arguably, superstition (CCC 2111).