Ikrimah narrates from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that when Umm Ibrahim gave birth to the son of the Prophet (peace and blessings be upon him), the Messenger of Allah (peace and blessings be upon him) said: "The child has set her free."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب المكاتب / 21783