‘Ikrimah said: ‘Ali burned some people who retreated from Islam. When Ibn ‘Abbas was informed of it, he said: If it had been I, I would not have burned them, for the Messenger of Allah (ﷺ) said: Do not inflict Allah’s punishment on anyone, but would have had killed them on account of the statement of the Messenger of Allah (ﷺ). The Apostle said: Kill those who change their religion. When ‘Ali was informed about it he said: How truly Ibn ‘Abbas said!
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَحْمَدُ بْنُ مُحَمَّدِ بْنِ حَنْبَلٍ، حَدَّثَنَا إِسْمَاعِيلُ بْنُ إِبْرَاهِيمَ، أَخْبَرَنَا أَيُّوبُ، عَنْ عِكْرِمَةَ، أَنَّ عَلِيًّا، عَلَيْهِ السَّلاَمُ أَحْرَقَ نَاسًا ارْتَدُّوا عَنِ الإِسْلاَمِ فَبَلَغَ ذَلِكَ ابْنَ عَبَّاسٍ فَقَالَ لَمْ أَكُنْ لأَحْرِقَهُمْ بِالنَّارِ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لاَ تُعَذِّبُوا بِعَذَابِ اللَّهِ " . وَكُنْتُ قَاتِلَهُمْ بِقَوْلِ رَسُولِ اللَّهِ صلى الله عليه وسلم فَإِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " مَنْ بَدَّلَ دِينَهُ فَاقْتُلُوهُ " . فَبَلَغَ ذَلِكَ عَلِيًّا عَلَيْهِ السَّلاَمُ فَقَالَ وَيْحَ ابْنَ عَبَّاسٍ .
sunnah.com