Vayeshev 

וישב

The Sages describe the pit into which the brothers cast Joseph, and their severe spiritual lapse. 

“They took him and cast him into the pit; and the pit was empty, there was no water in it” (Genesis 37:24). [Since if the pit were entirely empty, there would be no need to state that it did not contain water, one can infer:] There was no water in it, but there were serpents and scorpions in it. What did Simeon do? Once the brothers placed Joseph in the pit, Simeon commanded his brothers, and they cast large stones upon him in order to kill him. But when Simeon ultimately fell into Joseph’s custody in Egypt, Joseph did not exact revenge. Rather, he cast fattened birds upon him [i.e., fed him delicacies]. Rabbi Aha said: “And the pit was empty.” Jacob’s pit [i.e., his children] was emptied [i.e., they were devoid of wisdom]. The phrase “there was no water in it” teaches that there were no matters of Torah, likened to water, among the brothers. It is written: “If a man is found abducting any of his brethren of the children of Israel, and he enslaved him and sold him, that thief shall die” (Deuteronomy 24:7) – and you are selling your brother? <source>(Tanĥuma [Buber], Vayeshev; Bereshit Rabba [Theodor-Albeck] 84) </source>