Tafsir Ibn Abbas: Al-Hujuraat, Ayah 6

The following was revealed regarding al-Walīd b. ‘Uqba whom the Prophet had sent to the Banū al-Mustaliq in order to ascertain their loyalty to Islam. He already feared them on account of an old feud between him and them from the time of pagandom before Islam and so upon seeing them come out to him he returned and claimed that they had refused to give the voluntary alms and intended to kill him. And just as the Prophet s was making plans to raid them they came to him to disavow what he al-Walīd had said about them O you who believe if a reprobate should come to you with some tiding some piece of information verify it ascertain his truthfulness from his mendacity fa-tabayyanū a variant reading has fa-tathabbatū from al-thabāt ‘to ascertain’ lest you injure a folk an tusībū qawman an object denoting reason that is to say for fear of this happening out of ignorance bi-jahālatin is a circumstantial qualifier referring to the subject of the verb that is to say while you are ignorant; and then become remorseful of what you have perpetrated erroneously against that folk. After they had returned to their homelands the Prophet s sent Khālid b. al-Walīd to them who observed only obedience and goodness in them and later informed the Prophet of this.