Is it permissible to spend from donations designated for purchasing a mosque on what brings Muslims together, such as gatherings on Eids, especially since these gatherings increase donations?

Funds endowed for the purpose of purchasing a mosque may not be spent except for that purpose. It is not permissible to divert them for uniting Muslims and reconciling between them. This [latter] is a good deed for which other funds can be collected. As for the mosque's funds, they are an endowment, and it is not permissible to spend them on anything other than what they were designated for.