Doctrine of Life # 78
78. That to commit adultery also means to engage in obscene acts, to speak lasciviously, and to entertain filthy thoughts is clear from the Lord’s words in Matthew:
You have heard that it was said to those of old, “You shall not commit adultery.” But I say to you that whoever looks at (another’s) woman so as to lust for her has already committed adultery with her in his heart. (Matthew 5:27-28)
Jeremiah 3:8-9
8
I saw, when, for this very cause that backsliding Israel had committed adultery, I had put her away and given her a bill of divorce, yet treacherous Judah, her sister, didn't fear; but she also went and played the prostitute.
9
It happened through the lightness of her prostitution, that the land was polluted, and she committed adultery with stones and with stocks.