Safinah (RAA) narrated, ‘I was a slave of Umm Salamah and she said, ‘I shall emancipate you, but on the condition that you serve Allah’s Messenger (ﷺ) as long as you live.’ Related by Ahmad, Abu Dawud, An-Nasa’i and Al-Hakim.

وَعَنْ سَفِينَةَ ‏- رضى الله عنه ‏- { قَالَ: كُنْتُ مَمْلُوكًا لِأُمِّ سَلَمَةَ فَقَالَتْ: أُعْتِقُكَ, وَأَشْتَرِطُ عَلَيْكَ أَنْ تَخْدِمَ رَسُولَ اَللَّهِ ‏- صلى الله عليه وسلم ‏-مَا عِشْتَ } رَوَاهُ أَحْمَدُ, وَأَبُو دَاوُدَ, وَالنَّسَائِيُّ, وَالْحَاكِم ُ [1]‏ .‏