Is it obligatory to continue advising brothers to abandon "good innovations" (bid'ah hasanah) such as shaking hands after prayer, fasting on the 15th of Sha'ban, and congregational supplication after prayers, despite the psychological distress and the accusal of the advisor of Wahhabism?

Shaking hands after the prayer is an innovation (bid‘ah) that the Prophet, peace and blessings be upon him, did not do. Some jurists observed it regularly, but it has not been established as a Sunnah. It is considered reprehensible (makrooh) by some because it was not reported from the Companions and because it is among the practices of the Rawafid (a derogatory term for some Shia groups). Similarly, singling out the middle of Sha‘ban for fasting has no basis in the Sunnah. Fasting in the middle of Sha‘ban is like fasting in the middle of other months. The correct view is that singling it out for recitation or remembrance is an innovation. Group supplication (Du‘a) after prayer is an innovation that has no basis in Islamic law. What is prescribed is the remembrance (dhikr) and supplication (Du‘a) that are authentically reported to be recited individually by each worshiper after the salutation (tasleem). These issues require patience and wisdom when dealing with those who practice them, while being armed with sound Islamic knowledge.