Which is better: to hold the wedding feast in the mosque—while taking the necessary measures to preserve its cleanliness—or outside the mosque?

There is no evidence to suggest the superiority of holding a wedding feast (walimat an-nikah (definition)) in the mosque. It is preferable to hold it and invite people to it outside the mosque, especially if there is concern for its cleanliness. Scholars have differed regarding eating in the mosque: the Hanbalis and Shafi'is permitted it absolutely, while the Malikis differentiated between light, dry food, which is permissible, and other types, which are not permissible except out of necessity.