It's in the book of Joshua in the Bible. Chapter 24 verse 15. After the death of Moses, Joshua is leading the Israelites and asks them to decide whether they will follow the Lord God of the Israelites or whether they will turn back and follow the gods of the other peoples of that era. Joshua is recorded as having said "As for me and my household, we will serve the Lord." The people responded that they, too, would serve the Lord. Roughly translated, Joshua reminds them this is a serious commitment of the heart and to get rid of the foreign idols they've been carrying. That is, Joshua reminds them they can't promise to serve the Lord while at the same time hang onto foreign idols which represent the gods of the other peoples. Then, the people again promise to serve and obey the Lord.