Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says that Sayyiduna Umar (may Allah be pleased with him) made a kitabah contract with one of his slaves whose kunyah was Abu Umayyah. He came bringing his instalment. Umar said: "Take it back and seek help from it in your kitabah." He said: "O Commander of the Believers! If only you would leave it until it is the last instalment." He said: "I fear that I will not live to see that." Then he recited: "And give them from the wealth of Allah which He has given you" [Surah al-Nur: 33]. Ikrimah (may Allah have mercy on him) says: This was the first instalment paid in Islam.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب المكاتب / 21671