Sayyiduna Umar (may Allah be pleased with him) said: If she is a previously married woman (thayyib), a twentieth part (of the price) is returned with her; and if she is a virgin, a tenth part is returned.
Ali (al-Daraqutni) said: This is mursal; Amir did not meet Umar. Al-Shafi'i said: We do not know it to be established from Umar or from Ali, nor from either of them; and likewise some of the people of hadith who were present said that it is not established.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10746