From Sahih Muslim (Hadith 7558):
Sa'id b. Jubair reported:I said to Ibn 'Abbas about Sura Tauba, whereupon he said: As for Sura Tauba, it is meant to humiliate (the non-believers and the hypocrites). There is constantly revealed in it (the pronoun) minhum (of them) and minhom (of them, i. e. such is the condition of some of them) till they (the Muslims) thought that none would be left unmentioned out of them who would not be blamed (for one fault or the other). I again said: What about Sura Anfal? He said: It pertains to the Battle of Badr. I again asked him about Sura al-Hashr. He said: It was revealed in connection with (the tribe) of Banu Nadir
Reference: Muslim 7558