Devarim 18:9

לא תלמד לעשות THOU SHALT NOT LEARN TO DO [AFTER THE ABOMINATIONS OF THOSE NATIONS] — thou shalt not learn to do, but you may learn their practices in order to understand them and to teach others, that is to say, to understand their doings, how depraved they are, and thus to be able to teach thy children, “Do not so and so because these are the religious observances of the heathens!” (Sifrei Devarim 170:3; Sanhedrin 68a.)

כִּ֤י אַתָּה֙ בָּ֣א אֶל־הָאָ֔רֶץ אֲשֶׁר־יְהֹוָ֥ה אֱלֹהֶ֖יךָ נֹתֵ֣ן לָ֑ךְ לֹֽא־תִלְמַ֣ד לַעֲשׂ֔וֹת כְּתוֹעֲבֹ֖ת הַגּוֹיִ֥ם הָהֵֽם׃

When thou art come to the land which the Lord thy God gives thee, thou shalt not learn to do after the abominations of those nations.