Language:
كتاب الأدب
78  
Good Manners and Form (Al-Adab)
(80)
Chapter: "Make things easy for the people and do not make things difficult for them."
(80)
باب قَوْلِ النَّبِيِّ صلى الله عليه وسلم: «يَسِّرُوا وَلاَ تُعَسِّرُوا»
Sahih al-Bukhari 6126

Narrated `Aisha:

Whenever Allah's Messenger (ﷺ) was given the choice of one of two matters he would choose the easier of the two as long as it was not sinful to do so, but if it was sinful, he would not approach it. Allah's Apostle never took revenge over anybody for his own sake but (he did) only when Allah's legal bindings were outraged, in which case he would take revenge for Allah's sake." (See Hadith No. 760. Vol. 4)

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ أَنَّهَا قَالَتْ مَا خُيِّرَ رَسُولُ اللَّهِ صلى الله عليه وسلم بَيْنَ أَمْرَيْنِ قَطُّ إِلاَّ أَخَذَ أَيْسَرَهُمَا، مَا لَمْ يَكُنْ إِثْمًا، فَإِنْ كَانَ إِثْمًا كَانَ أَبْعَدَ النَّاسِ مِنْهُ، وَمَا انْتَقَمَ رَسُولُ اللَّهِ صلى الله عليه وسلم لِنَفْسِهِ فِي شَىْءٍ قَطُّ، إِلاَّ أَنْ تُنْتَهَكَ حُرْمَةُ اللَّهِ، فَيَنْتَقِمَ بِهَا لِلَّهِ‏.‏
Reference : Sahih al-Bukhari 6126
In-book reference : Book 78, Hadith 153
USC-MSA web (English) reference : Vol. 8, Book 73, Hadith 147
  (deprecated numbering scheme)