Is it permissible to invite people to weddings from within the mosque?

It appears there is no harm in inviting people to wedding feasts in mosques, as long as it does not disturb those performing prayers. This is because it falls under what is considered good and is not among the things explicitly forbidden in a mosque, such as announcing lost property and the like. However, anything that leads to disturbing those praying is not permissible in the mosque. Some scholars have permitted it because the Prophet (peace be upon him) عقد النكاح (performed the marriage contract) inside the mosque and married off the woman who offered herself to him inside it. Others, however, have prohibited it, arguing that mosques were not built for such purposes. The more cautious approach is to avoid it, but if custom permits it, they should not be criticized.

Speech in the mosque is of two types: First, that which disturbs those praying and reciting the Quran, which is not permissible. Second, that which does not disturb. If it pertains to good matters, then it is good. If it pertains to worldly matters, some of it is forbidden, such as trade and announcing lost property, and some of it is permissible, such as truthful conversation free from prohibitions.