Hadith 9:29
Ibn Fudayl narrated to us, from Layth, from Tawus, who said: A woman who had become pregnant was brought to Umar. She said, "I married with the testimony of my mother and my sister." He separated them and averted the prescribed punishment (hadd) from them. He said, "There is no marriage except with a guardian, and there is no marriage except with witnesses."
حدثنا بن فضيل عن ليث عن طاوس قال أتي عمر بامرأة قد حملت فقالت تزوجت بالشهادة من أمي وأختي ففرق بينهما ودرأ عنهما الحد وقال لا نكاح إلا بولي ولا نكاح إلا بشهود