Deuteronomy 8:19

8:19 Now if you forget the Lord your God at all and follow other gods, worshiping and prostrating yourselves before them, I testify to you today that you will surely be annihilated.

Deuteronomy 13:2

13:2 and the sign or wonder should come to pass concerning what he said to you, namely, “Let us follow other gods” – gods whom you have not previously known – “and let us serve them.”