Sahih Bukhari Volume 4, Book 61, Hadith 3562

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، أَخْبَرَنَا مَالِكٌ، عَنِ ابْنِ شِهَابٍ، عَنْ عُرْوَةَ بْنِ الزُّبَيْرِ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ أَنَّهَا قَالَتْ مَا خُيِّرَ رَسُولُ اللَّهِ صلى الله عليه وسلم بَيْنَ أَمْرَيْنِ إِلاَّ أَخَذَ أَيْسَرَهُمَا، مَا لَمْ يَكُنْ إِثْمًا، فَإِنْ كَانَ إِثْمًا كَانَ أَبْعَدَ النَّاسِ مِنْهُ، وَمَا انْتَقَمَ رَسُولُ اللَّهِ صلى الله عليه وسلم لِنَفْسِهِ، إِلاَّ أَنْ تُنْتَهَكَ حُرْمَةُ اللَّهِ فَيَنْتَقِمَ لِلَّهِ بِهَا‏.‏

Narrated By 'Aisha : Whenever Allah's Apostle 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 to do so, 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.