Is it permissible to give food as charity to worshippers inside the mosque?

If the question is about giving food as charity to the people of the mosque for them to eat, there is no harm in that, even if they are wealthy. This is because voluntary charity (sadaqat al-tatawwu') is permissible for the rich, and it is treated like a gift, though it is disliked for the wealthy to expose themselves to taking it. There is no harm in eating inside the mosque if there is no risk of soiling it. This is supported by the permissibility of eating bread and meat in the mosque during the time of the Messenger of Allah, peace and blessings be upon him, and the residence of the Ashab al-Suffah therein.