Khalid bin Salamah al-Makhzumi (may Allah have mercy on him) narrates that a man came to Sayyiduna Umar (may Allah be pleased with him) at Arafah and said: "I set free my share of this slave." He said: "Set him free entirely, for Allah has no partner."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العتق / 21318