(14) باب فَضِيلَةِ إِعْتَاقِهِ أَمَتَهُ ثُمَّ يَتَزَوَّجُهَا
Abu Musa reported that Allah's Messenger (ﷺ) said about one who emancipated a slave woman, and then married her, that for him there are two rewards.
Reference: Sahih Muslim 154 b
In-book reference: Book 16, Hadith 101
USC-MSA web (English) reference(deprecated numbering scheme): Book 8, Hadith 3327