Midrash su Giobbe 24:21

"And Enoch begat Erad..." Rabbi Yehoshua ben Levi said: They all refer to rebellion. Erad - I will drive him out from the world. Mechuya'el - I will erase him from the world. Metusha'el - I will weaken him from the world. Lemech - What do I need with Lemech and his descendents? "And Lemech took for himself two wives, one was named Adah and the second was named Tzilah" (Genesis 4:19). Rabbi Azariah said in the name of Rabbi Yehudah bar Simon: this is what the men of the generation of the Flood would do: each of them would take two wives, one for procreation and one for pleasure. The one who was for procreation would sit as if she was a widow in her own lifetime (in the lifetime of her husband), and the one that was for pleasure would drink a cup for sterility so that she did not bear [children], and would sit by him adorned like a prostitute. As it is written: "He devours the barren that do not conceive, and does not do good to the widow" (Job 24:21). Know that among them the best was Lemech, and he took two wives, as it says "And Lemech took for himself two wives, one was named Adah" - because she became pregnant [adah] "and the second was named Tzilah" - because she sat in his shade [tzel].