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كتاب المغازى
64  
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
Sahih al-Bukhari 4057

Narrated Ibn Al Musaiyab:

Sa`d bin Abi Waqqas said, "Allah's Messenger (ﷺ) mentioned both his father and mother for me on the day of the battle of Uhud." He meant when the Prophet (ﷺ) said (to Sa`d) while the latter was fighting. "Let my father and mother be sacrificed for you!"

حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا لَيْثٌ، عَنْ يَحْيَى، عَنِ ابْنِ الْمُسَيَّبِ، أَنَّهُ قَالَ قَالَ سَعْدُ بْنُ أَبِي وَقَّاصٍ ـ رضى الله عنه ـ لَقَدْ جَمَعَ لِي رَسُولُ اللَّهِ صلى الله عليه وسلم يَوْمَ أُحُدٍ أَبَوَيْهِ كِلَيْهِمَا‏.‏ يُرِيدُ حِينَ قَالَ ‏ "‏ فِدَاكَ أَبِي وَأُمِّي ‏"‏‏.‏ وَهُوَ يُقَاتِلُ‏.‏
Reference : Sahih al-Bukhari 4057
In-book reference : Book 64, Hadith 103
USC-MSA web (English) reference : Vol. 5, Book 59, Hadith 387
  (deprecated numbering scheme)