John Wesley on 1 Corinthians 7:12

To the rest - Who are married to unbelievers. Speak I - By revelation from God, though our Lord hath not left any commandment concerning it. Let him not put her away - The Jews, indeed, were obliged of old to put away their idolatrous wives, Ezra 10:3; but their case was quite different. They were absolutely forbid to marry idolatrous women; but the persons here spoken of were married while they were both in a state of heathenism.