Sahih al-Bukhari 3946
Sahih al-Bukhari · Book 63: Merits of the Helpers in Madinah (Ansaar) · The conversion of Salman Al-Farisi to Islam رضي الله عنه
Narrated Salman Al-Farisi:
حَدَّثَنِي الْحَسَنُ بْنُ عُمَرَ بْنِ شَقِيقٍ ، حَدَّثَنَا مُعْتَمِرٌ ، قَالَ أَبِي وَحَدَّثَنَا أَبُو عُثْمَانَ ، عَنْ سَلْمَانَ الْفَارِسِيِّ ، أَنَّهُ تَدَاوَلَهُ بِضْعَةَ عَشَرَ مِنْ رَبٍّ إِلَى رَبٍّ.
That he was sold (as a slave) by one master to another for more than ten times (i.e between 13 and 19).