Tafsir Ibn Abbas: Al-Baqara, Ayah 85

Then there you are killing one another and expelling a party of you from their habitations conspiring tazzāharūna the original ta’ has been assimilated with the zā’; a variant reading has it without the assimilation that is tazāharūna assisting one another against them in sin in disobedience and enmity injustice and if they come to you as captives a variant reading for usārā has asrā you ransom them a variant reading for tafdūhum has tufādūhum that is to say you deliver them from captivity with money etc. and this ransoming was one of the things to which they were pledged; yet their expulsion was forbidden you muharramun ‘alaykum ikhrājuhum is semantically connected to wa-tukhrijūna ‘and expelling’ and the statement that comes in between is parenthetical that is expulsion was forbidden you in the same way that non-ransoming was forbidden you. Qurayza had allied themselves with the Aws and the Nadīr with the Khazraj but every member of an alliance would fight against a fellow ally thus destroying each other’s homes and expelling one another taking prisoners and then ransoming them. When they were asked ‘Why do you fight them and then pay their ransom?’ they would reply ‘Because we have been commanded to ransom’; and they would be asked ‘So why do you fight them then?’ to which they would say ‘For fear that our allies be humiliated’; God exalted says What do you believe in part of the Book that is the part about ransom and disbelieve in part? namely the part about renouncing fighting expulsion and assistance against one another; What shall be the requital of those of you who do that but degradation disgrace and ignominy in the life of this world they were disgraced when Qurayza were slewn and the Nadīr were expelled to Syria and ordered to pay the jizya; and on the Day of Resurrection to be returned to the most terrible of chastisement? And God is not heedless of what you do ta‘malūna or read ya‘malūna ‘they do’.