Is it permissible to record a sermon (or khutbah) and send it on Friday to a group of people via WhatsApp, with the aim of strengthening communal bonds and reminding them of the special nature of Friday, especially in Europe, or is this considered an innovation (bid‘ah)?

May Allah reward you for your eagerness to call to Allah. As for what you do, if the sermon is not linked to the Dhuhr prayer, but rather you record it whenever convenient, then send it to those who listen to it at their suitable time, and they do not link their Dhuhr prayer to it, then there is no harm in it; because it is a sermon like any other sermon.

However, if it is linked to the Dhuhr prayer, such that they do not pray Dhuhr until after listening to it, and they make that a habit, then we do not see its permissibility; because the sermon was legislated for Jumu'ah, not Dhuhr. And whoever is unable to attend Jumu'ah prays Dhuhr without a sermon. Furthermore, persistently doing so may lead to the belief that this is legislated, thus creating an innovation (bid'ah). Many innovations begin as something deemed good (istihsan) and then become a followed religion.

This deeming good is based on intellect without referring to the Qur'an and Sunnah, which is what Ash-Shafi'i invalidated by saying: "Whoever deems good has legislated." The desired benefit from listening to the sermon can be achieved at another time by gathering to listen to a lecture or lesson without linking it to the Dhuhr prayer.