Midrasch zu Wajikra 24:1

“And Israel abode in Shittim…” (Bamidbar 25:1) This is the law. Israel was redeemed from Egypt in the merit of many things. Our Rabbis taught: Israel was redeemed from Egypt in the merit of four things. They did not change their names, they did not change their language, they did not reveal their secrets. Moshe said to them “…and every woman shall ask of her neighbor, and of her that live in her house, vessels of silver and vessels of gold…” (Shemot 3:22) They kept this command hidden between them for twelve months and not one of them revealed it to the Egyptians. They did not breakdown into forbidden sexual relationships, as it is written “A locked up garden is my sister, my bride…” this refers to the men, “…a locked up spring, a sealed fountain,” (Shir HaShirim 4:12) and this refers to the virgins. You should know this, because there was one who transgressed and the Torah publicized it “Now, the son of an Israelite woman and he was the son of an Egyptian man went out among the children of Israel…” (Vayikra 24:1) All the forty years in the wilderness they did not go astray until they came to Shittim. Therefore it says “And Israel abode in Shittim, and the people began to commit harlotry…” (Bamidbar 25:1) It was called Shittim because there they did foolishness (shtut), “He who commits adultery with a woman lacks understanding…” (Mishle 6:32) ‘the people began to commit harlotry’ There are springs which raise mighty people and there are those that raise weaklings, those that raise beautiful people and those that raise ugly ones, those that raise modest people and those that raise people steeped in licentiousness. The spring of Shittim was one of harlotry, and it watered Sodom. You find that they said “Where are the men who came in to you? Bring them out to us…” (Bereshit 19:5) Since that spring was accursed, in the future the Holy One will dry it out, as it says “…and a spring will issue from the house of the Lord and will water the valley of Shittim…” (Yoel 4:18) From the days of Avraham no one had broken out in harlotry. Once they arrived at Shittim and drank from its waters, they burst forth.