Sunan Ibn Majah 1956
It was narrated from Abu Musa that the Messenger of Allah said:
'Whoever has a slave woman and teaches her good manners and educates her, then sets her free and marries her, will have two rewards. Any man from among the People of the Book who believed in his Prophet and believed in Muhammad will have two rewards. Any slave who does his duty towards Allah and towards his masters will have two rewards.” (Sahih)(one of the narrators) Salih said: “Sha'bi said: 'I have given this (Hadith) to you for little effort on your part. A rider would travel to Al-Madinah for less than this.'  ”
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ سَعِيدٍ أَبُو سَعِيدٍ الأَشَجُّ، حَدَّثَنَا عَبْدَةُ بْنُ سُلَيْمَانَ، عَنْ صَالِحِ بْنِ صَالِحِ بْنِ حَىٍّ، عَنِ الشَّعْبِيِّ، عَنْ أَبِي بُرْدَةَ، عَنْ أَبِي مُوسَى، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ‏
"‏ مَنْ كَانَتْ لَهُ جَارِيَةٌ فَأَدَّبَهَا فَأَحْسَنَ أَدَبَهَا وَعَلَّمَهَا فَأَحْسَنَ تَعْلِيمَهَا ثُمَّ أَعْتَقَهَا وَتَزَوَّجَهَا فَلَهُ أَجْرَانِ وَأَيُّمَا رَجُلٍ مِنْ أَهْلِ الْكِتَابِ آمَنَ بِنَبِيِّهِ وَآمَنَ بِمُحَمَّدٍ فَلَهُ أَجْرَانِ وَأَيُّمَا عَبْدٍ مَمْلُوكٍ أَدَّى حَقَّ اللَّهِ عَلَيْهِ وَحَقَّ مَوَالِيهِ فَلَهُ أَجْرَانِ ‏"‏ ‏.‏ قَالَ صَالِحٌ قَالَ الشَّعْبِيُّ قَدْ أَعْطَيْتُكَهَا بِغَيْرِ شَىْءٍ ‏.‏ إِنْ كَانَ الرَّاكِبُ لَيَرْكَبُ فِيمَا دُونَهَا إِلَى الْمَدِينَةِ ‏.‏