Rashi on Genesis 37:24/רש"י על בראשית ל״ז:כ״ד

1והבור רק אין בו מים AND THE PIT WAS EMPTY, THERE WAS NO WATER IN IT — Since it states, “the pit was empty”, do I not know that “there was no water in it”? What then is the force of “there was no water in it”? Water, indeed it did not contain, but there were serpents and scorpions in it (Shabbat 22a).