Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) bought a slave girl from his wife Zaynab Thaqafiyyah. His wife sold her on the condition that whenever you wish to sell this slave girl, sell her to me for whatever price you agree to sell her for. Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) mentioned this matter to Sayyiduna Umar (may Allah be pleased with him), and he said: Do not have relations with a slave girl in whom there is someone else's condition.