Quran 33:53 — The Parties (Al-Ahzab)

O you who believe, do not enter the prophet's homes unless you are given permission to eat, nor shall you force such an invitation in any manner. If you are invited, you may enter. When you finish eating, you shall leave; do not engage him in lengthy conversations. This used to hurt the prophet, and he was too shy to tell you. But GOD does not shy away from the truth. If you have to ask his wives for something, ask them from behind a barrier. This is purer for your hearts and their hearts. You are not to hurt the messenger of GOD. You shall not marry his wives after him, for this would be a gross offense in the sight of GOD.*

[33:52] Beyond the categories described to you, you are enjoined from marrying any other women, nor can you substitute a new wife (from the prohibited categories), no matter how much you admire their beauty. You must be content with those already made lawful to you. GOD is watchful over all things.

[33:54] Whether you declare anything, or hide it, GOD is fully aware of all things.