Parashas Eikev · Passuk 7:26
You must not bring an abhorrent thing into your house, or you will be proscribed like it; you must reject it as abominable and abhorrent, for it is proscribed.
Torah Temimah points to Temurah 30b.
TT lemma: והיית חרם כמהו (unit 5 of 7).
English: Rav Achdavu bar Ami said in the name of Rav: If one betroths a woman with the dung of worshipped calves, the betrothal is ineffective, as it is written, “you shall be a ban like it”; whatever derives from it is like it.
Custom (dung of idolatrous calves — kiddushin)
Even dung generated from idolatrous animals cannot effect betrothal; it is treated like the ban itself.