Abu Dawud reported the Apostle of Allaah ﷺ as saying “Anyone who sets his slave girl free and then marries her, will have a double reward.”  

قَالَ رَسُولُ اللَّهِ ﷺ مَنْ أَعْتَقَ جَارِيَتَهُ وَتَزَوَّجَهَا كَانَ لَهُ أَجْرَانِ  

Anas bin ‘Malik said “The Prophet ﷺ manumitted Safiyyah and made her manumission her dower.”  

أَنَّ النَّبِيَّ ﷺ أَعْتَقَ صَفِيَّةَ وَجَعَلَ عِتْقَهَا صَدَاقَهَا