Hazrat Ibn Umar (may Allah be pleased with them both) narrates that Hazrat Umar said: If a man is brought to me who has had intercourse with his wife's concubine, I will certainly stone him to death.

Hazrat Nafi’ reports that a slave girl came to Hazrat Umar and said: O Commander of the Faithful! Indeed, Hazrat Mughira has intercourse with me and his wife calls me an adulteress. So if I am the property of his wife, then stop him from having intercourse with me, and if I am the property of Mughira, then stop his wife from accusing me. Upon this, Hazrat Umar sent a messenger to call Hazrat Mughira and asked: Do you have intercourse with this slave girl? He replied: Yes. Hazrat Umar asked: Where did you get her from? He replied: My wife gifted her to me as a gift. Hazrat Umar said: By Allah! If she has not gifted this slave girl to you, you will not return home today except after receiving lashes. Then Hazrat Umar ordered so-and-so and so-and-so and said: Both of you go to Mughira’s wife and inform her about this matter. If you have not gifted this slave girl to him, we will surely stone her. So both men went to Hazrat Mughira’s wife and informed her about the matter. She said: Alas! Do they intend to stone my husband? Then Allah settled the matter through her statement, and she said: Indeed, I have gifted that slave girl to him. So Hazrat Umar let them go.

Ibrahim narrates that a man came to Hazrat Ibn Mas'ud and said: "Indeed, I have had intercourse with my wife's slave-girl." Upon this, he (Ibn Mas'ud) said: "Surely Allah has concealed your sin, so you too conceal it." This matter reached Hazrat Ali (may Allah be pleased with him), so he said: "If the person who came to Ibn Umm Abd had come to me, I would certainly have crushed his head with stones."