Ezra 9: 1-2 (NKJV)
"When these things were done, the leaders came to me, saying, “The people of Israel and the priests and the Levites have not separated themselves from the peoples of the lands, with respect to the abominations of the Canaanites, the Hittites, the Perizzites, the Jebusites, the Ammonites, the Moabites, the Egyptians, and the Amorites. For they have taken some of their daughters as wives for themselves and their sons, so that the holy seed is mixed with the peoples of those lands. Indeed, the hand of the leaders and rulers has been foremost in this trespass."
2 Corinthians 6: 31 (NKJV)
"Do not be unequally yoked together with unbelievers. For what fellowship has righteousness with lawlessness? And what communion has light with darkness? And what accord has Christ with Belial? Or what part has a believer with an unbeliever? And what agreement has the temple of God with idols? For you are the temple of the living God. As God has said: “I will dwell in them and walk among them. I will be their God, and they shall be my people.” Therefore “Come out from among them and be separate, says the Lord. Do not touch what is unclean, and I will receive you.” “I will be a Father to you, and you shall be my sons and daughters, says the LORD Almighty."