Commentary for Genesis 37:24

והבור 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).

אין בו מים. If the pit had been full of water the brothers would not have thrown him into the pit, as they then would have been guilty of drowning him, i.e. killing him with their own hands, as it were. They had said themselves “let not our hands be on him.”

ויקחהו, there is a letter ו missing in this word, making it appear as if only one brother took him. According to Bereshit Rabbah 84,16 this is an allusion to who the brother was who seized Joseph and threw him into the pit. It was Shimon, which was the reason why later on Joseph locked up Shimon as a hostage (42,24 ויקח מאתם את שמעון, he took Shimon from them.)