The 42nd prohibition is that we are forbidden from wearing a garment woven1 from wool and linen, as the idolatrous priests of that time used to wear.2

The source of this commandment is G‑d's statement,3 "Do not wear shatnez."

This practice is well known even today among Coptic monks in Egypt.

One who transgresses this prohibition is punished by lashes.

The details of this mitzvah are explained in tractate Kilayim,4 as well as in tractate Shabbos5 and the end of tractate Makkos.6