Sforno on Numbers 21:14/ספורנו על במדבר כ״א:י״ד

1בספר מלחמות ה' את והב בסופה, [if I understand the author correctly he suggests that the waters of the rock at Massah Umerivah which he described as flowing upstream, anti gravity like, were the reason why Sichon did not attempt to oppose the Israelites at the time when they first entered territory which was under his sovereignty. Ed.] Some of these miraculous events are recorded in what are known as the book of G’d’s wars. Examples of such miracles were what happened here and how these waters described a turn returning to their origin, i.e. the well that originated at Massah and Merivah. The reason why the Torah is so vague about these miracles is out of consideration for Moses and Aaron. The reason for these miracles was only in order to demonstrate to the Israelites what kind of miracles they had not been shown because Moses and Aaron had decided not to speak to the rock at the time. The people only found out in retrospect that the waters which had come forth from that rock were not natural waters, subject to the laws of nature such as the laws of gravity. These waters also did not behave according to the laws of centrifugality, i.e. of instead displaying a tendency of flowing towards the center. This is why these waters ascended with the Jewish people in their journeys through mountainous regions. [I have summarised the author’s commentary on these verses in order for the reader not to lose track of the main thrust of this commentary. Ed.]