I asked, "Messenger of Allah, what removes from me the obligation owed for nursing?"He replied, "A slave, male or female."
أخبرنا يعقوب بن إبراهيم قال حدثنا يحيى عن هشام قال وحدثني أبي
قلت يا رسول الله ما يذهب عني مذمة الرضاع قال غرة عبد أو أمة
Referenced. Its isnad is hasan. Abu Dawud narrated it in the book of Nikah, chapter on giving a gift at weaning, no. 2064, and Tirmidhi narrated it in the book of Rada, chapter on what discharges the debt of breastfeeding, no. 1153, from the hadith of Hisham bin Urwa. Ibn Hibban graded it sahih. It is also transmitted through Urwa, and it appears in Sunan al-Kubra, no. 5482. Tirmidhi said, hasan sahih, and it has many corroborating narrations (Majma al-Zawaid 4/262 and elsewhere).