What is the evidence – from Arabic language books, not from poetry – for the permissibility of attributing a statement to a group or community, even if not all of them say it?

Attributing speech to a group when only some of them are meant is a well-established Arabic linguistic style. Examples from the Quran include: attributing the saying "Indeed, the people have gathered against you" to "the people" even though only one person said it; attributing the good thought in the incident of the slander (Al-Ifk) to "the believing men and believing women" even though it was said by Abu Ayyub and his wife; and attributing the hamstringing of the she-camel to "So they hamstrung the she-camel" even though only one person hamstrung it. This is because they were all content with the action. Imam Al-Shafi'i established this principle, and other scholars such as Imam Al-Tabari, Al-Zamakhshari, and Ibn Faris mentioned that Arabs express news using the plural form when referring to a singular entity, if the news is not attributed to a specific individual, or if the action is done with the consent of the group.