Language:
كتاب الإكراه
89  
(Statements made under) Coercion
(1)
Chapter: Whoever preferred to be beaten killed and humiliated rather than to revert to Kufr
(1)
باب مَنِ اخْتَارَ الضَّرْبَ وَالْقَتْلَ وَالْهَوَانَ عَلَى الْكُفْرِ
Sahih al-Bukhari 6941

Narrated Anas:

Allah's Messenger (ﷺ) said, "Whoever possesses the (following) three qualities will have the sweetness of faith (1): The one to whom Allah and His Apostle becomes dearer than anything else; (2) Who loves a person and he loves him only for Allah's Sake; (3) who hates to revert to atheism (disbelief) as he hates to be thrown into the Fire."

حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ حَوْشَبٍ الطَّائِفِيُّ، حَدَّثَنَا عَبْدُ الْوَهَّابِ، حَدَّثَنَا أَيُّوبُ، عَنْ أَبِي قِلاَبَةَ، عَنْ أَنَسٍ ـ رضى الله عنه ـ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ ثَلاَثٌ مَنْ كُنَّ فِيهِ وَجَدَ حَلاَوَةَ الإِيمَانِ أَنْ يَكُونَ اللَّهُ وَرَسُولُهُ أَحَبَّ إِلَيْهِ مِمَّا سِوَاهُمَا، وَأَنْ يُحِبَّ الْمَرْءَ لاَ يُحِبُّهُ إِلاَّ لِلَّهِ، وَأَنْ يَكْرَهَ أَنْ يَعُودَ فِي الْكُفْرِ، كَمَا يَكْرَهُ أَنْ يُقْذَفَ فِي النَّارِ ‏"‏‏.‏
Reference : Sahih al-Bukhari 6941
In-book reference : Book 89, Hadith 2
USC-MSA web (English) reference : Vol. 9, Book 85, Hadith 74
  (deprecated numbering scheme)