Maymun bin Mihran (may Allah have mercy on him) says that Ibn Umar (may Allah be pleased with them both) made a kitabah contract with his slave. When the time came, the slave came bringing something. Ibn Umar (may Allah be pleased with them both) asked: "Where is this from?" He said: "I have been begging from people and working." He said: "Would you feed me the dirt of people? Go, you are free, and this portion is also yours."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب المكاتب / 21666