Midras Hakim-hakim 11:25: Midrash Lekach Tov

And Israel settled in Shittim. Balak and all his people of Pethor took counsel and said, "We have no choice but to seek the advice of Balaam." Balaam... Balaam gave his advice. Balak came to curse the people of Israel. It is written in one place (Joshua 24:9), "And he fought against Israel." And in another place (Judges 11:17), "If we fight with them." But he came to fight, and it did not go well. Immediately they went and entrusted their daughters, as our sages said regarding the "remembered above" matter. Therefore, it is said, "And Israel settled in Shittim, and the people began to commit sexual immorality with the daughters of Moab." And it says (Numbers 31:16), "These caused the children of Israel to sin." Weren't they brought from Midian? Rather, it teaches us that Midian and Moab were in this advice that Balaam gave in order to cause Israel to stumble. When Israel saw that Balaam had no power to curse them, they immediately fell into immorality, and 24,000 of them perished. "In Shittim" means that they engaged in foolishness. As it is also said (Proverbs 7:7), "The adulterous woman lacks sense." Another interpretation: "And Israel settled in Shittim." Whenever the term "settling" is mentioned, it is a language of distress. It is said regarding Cain (Genesis 4:16), "And Cain went out from the presence of the Lord and settled in the land of Nod." (Genesis 37:1) "And Jacob settled." Joseph was sold. (Exodus 32:6) "And the people sat down to eat and drink." And they handed over Joseph. (Exodus 32:6) "And the people sat down to eat and drink, and they got up to play." And Israel settled in Shittim, and there were deaths, and the people began to commit sexual immorality with the daughters of Moab. They made profane what was once holy. "The daughters of Moab" refers to the plains of Moab on the eastern side of the Jordan. For the wilderness of Jeshimon is to the west of the land of Moab, close to the Jordan, as it is a day's journey.