Abu Mu'ammal (may Allah be pleased with him) was the man who was the first to make a contract of manumission (mukatabah) in Islam, in the time of the Prophet (peace and blessings be upon him). He (peace and blessings be upon him) said: "Help Abu Mu'ammal." So I was helped; I was given so much wealth that after (paying) the contract of manumission something was left over, and he (peace and blessings be upon him) said: "Spend it in the path of Allah."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الصدقات / 13191