Sefer HaChinuch ספר החינוך

To not follow the practices of the gentiles: To not follow the practices of the Amorites and so [too,] the practices of the gentiles, as it is stated (Leviticus 20:23), “And you shall not follow the practice of the nation that I am driving out before you.” And the law is the same for all the nations, since the matter is that they turn away from [following] God, and worship idolatry. And the content of the commandment is that we not behave like them in our clothing and our matters. And it is like they said in Sifra, Acharei Mot, Chapter 13:8, “‘And do not follow their practices — that you not follow their mores with things that are fixed for them, such as theaters, circuses and amphitheaters” — and all of these are types of frivolity that they would do in their gatherings, when they gathered to do craziness, licentiousness and idolatry. And they said there, “‘The practice of the nation’ — Rabbi Meir says, ‘These are the ways of the Amorites that the Sages numbered.’ (See Shabbat 67a.) Rabbi Yehudah ben Beteira says, ‘That you should not grow a tassel of the head and not cut its growth’” — meaning to say that he not shave from the sides and leave hair in the middle, which is called a forelock. And this negative commandment is repeated in another place with other words, as it is stated (Deuteronomy 12:30), “Guard yourself lest you be ensnared to follow them.” And the language of Sifrei is “‘Guard’ is with a negative commandment; ‘lest’ is with a negative commandment; ‘you be ensnared to follow them’ is lest you imitate them and do like their deeds; ‘and it shall be a snare for you’ is that you not say, ‘Since they go out with velvet, I will go out with velvet, since they go with helmets, I will go with a helmet’” — and that is a type of knight’s armor. And the language of the books of prophecy (Zephaniah 1:8) is “and upon all of the dressed, there is a foreign dress.”

It is from the roots of the commandment [that it is] in order to distance ourselves from them and disparage all of their customs, and even in dress.

We have written a little from the laws of the commandment. And they, may their memory be blessed, brought some of these, along with the rest of its details, in the seventh chapter of Shabbat and in (Chapter 8 of the) Tosefta of Shabbat. (See Tur, Yoreh Deah 177.)

And [it] is practiced in every place and at all times by males and females. And one who transgresses it and does a thing of those that we mentioned, to imitate them, is liable for lashes. And one who distances himself from all of their customs and from all of their mores, and places all of his heart and his thoughts to God, may He be blessed, and to His precious commandments, “his soul will rest in the good, and his seed will inherit the Land.”