If I repair something in the Masjid (mosque), will it be considered as Sadaqah (voluntary charity)
or not? What is the ruling on doing this, even though the Masjid has some Waqf (endowment) farms?
That will be regarded as Sadaqah and a good deed, whether the Masjid has some farms or not. But you should not spend Zakah (obligatory charity) on this Masjid. You will be rewarded for this Sadaqah if you give it sincerely for the Sake of Allah and it was earned in a Halal (lawful) way.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.