Umm Salama freed me on the condition that I serve the Prophet ﷺ for as long as he lived.
حدثنا عبد الله بن معاوية الجمحي حدثنا حماد بن سلمة عن سعيد بن جمهان
أعتقتني أم سلمة واشترطت علي أن أخدم النبي ﷺ ما عاش
Its chain of transmission is hasan. Abu Dawud narrated it in the chapter on freeing a slave upon a condition, in the book of manumission, hadith no. 3932, from the hadith of Saeed, transmitted through him. Ibn Jarud graded it sahih, hadith no. 976, as did Hakim, 2/213–214, and Dhahabi.