Malik related to me from Rabia ibn Abi Abd ar-Rahman that Umaribn al-Khattab spoke about a man who went out with his wife's slave-girl on a journey and had intercourse with her and then the wifebecame jealous and mentioned that to Umar ibn al-Khattab. Umarquestioned him about it. He said, "She gave her to me." Umar said,"Bring me a clear proof or I will stone you." Rabia added, "The wifeconfessed that she had given her to him."
USC-MSA web (English) reference: Book 41, Hadith 20
Arabic reference: Book 41, Hadith 1523