حَدَّثَنَا مُحَمَّدُ بْنُ رُمْحٍ، أَنْبَأَنَا اللَّيْثُ بْنُ سَعْدٍ، عَنْ أَبِي الزُّبَيْرِ، عَنْ جَابِرٍ، قَالَ جَاءَ عَبْدٌ فَبَايَعَ النَّبِيَّ صلى الله عليه وسلم عَلَى الْهِجْرَةِ وَلَمْ يَشْعُرِ النَّبِيُّ صلى الله عليه وسلم أَنَّهُ عَبْدٌ فَجَاءَ سَيِّدُهُ يُرِيدُهُ فَقَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ بِعْنِيهِ ‏"‏ ‏.‏ فَاشْتَرَاهُ بِعَبْدَيْنِ أَسْوَدَيْنِ ثُمَّ لَمْ يُبَايِعْ أَحَدًا بَعْدَ ذَلِكَ حَتَّى يَسْأَلَهُ أَعَبْدٌ هُوَ

It wasnarrated that Jabir said: “A slave came and gave his pledge totheProphet (PBUH), pledging to emigrate, and the Prophet (PBUH) did notrealize that he was a slave. Then his master came looking for him,andthe Prophet (PBUH) said: ‘Sell him to me,’ and he brought himinexchange for two black slaves. Then after that he did not acceptthepledge from anyone until he had asked whether he was a slave.” Translation Not Available

Book Ref: Sunan Ibn Majah Book 24 Hadith 2869
Web Ref:  Sunan Ibn Majah Vol 4 Book 24 Hadith 2869