Yahya bin Hatib narrated that when Hatib passed away, he freed from among his slaves anyone who had performed prayers and kept fasts. He had a Nubian slave woman who had also performed prayers and kept fasts, and she was a non-Arab. Her pregnancy troubled him. He went to Umar (may Allah be pleased with him) and informed him of this matter. Umar (may Allah be pleased with him) said, "You never bring good news," and this statement troubled him. Then Umar (may Allah be pleased with him) sent a message to the slave woman and asked, "Are you pregnant?" She replied, "Yes, from Mar'ush in exchange for two dirhams (due to committing adultery)." It was as if she was not hiding the matter out of ignorance. Then Umar (may Allah be pleased with him) encountered Ali, Uthman, and Abdur Rahman bin Awf (may Allah be pleased with them) and said, "Advise me." Uthman (may Allah be pleased with him) was sitting reclining, and Ali and Abdur Rahman bin Awf (may Allah be pleased with them) said, "The hadd (punishment) will be enforced upon her." Then he (Umar) said, "O Uthman, advise me." He replied, "Your two brothers have already advised you." He said, "Advise me." So he said, "In my opinion, she considers this matter light due to not knowing (its seriousness), and the hadd is only enforced upon one who knows its prohibition." Umar (may Allah be pleased with him) said, "You have spoken the truth. By Him in Whose hand is my soul, the hadd is only for the one who knows." Then Umar (may Allah be pleased with him) ordered her to be flogged one hundred lashes and exiled for one year.
Hadith Referenceمسند الإمام الشافعي / كتاب الحدود / 1582
Hadith Takhrijاسناده ضعيف جدا، لضعف مسلم بن خالد الزنجى و لعنعنة ابن جريج ولا نقطاعه فان يحي بن عبدالرحمن بن حاطب لم يسمع من عمر اخرجه البيهقي: 8/ 238 ، 239 - وفى المعرفة السنن والآثار له (5093)۔ وعبد الرزاق (13644)۔