What is the Sharʿi ruling regarding shunning, rejecting, and boycotting the imams and khatibs of mosques after offering them advice and correction with Sharʿi evidences? And what is the Sharʿi ruling for someone who knows of their error but does not correct them?

Advice is an act of worship through which a servant draws closer to Allah, for the Prophet, peace and blessings be upon him, said: "Religion is advice." It is a collective obligation (fard kifayah) and is obligatory to the extent of one's ability, provided its consequences are safe. Otherwise, it is permissible to forgo it. The Imam must be advised if he mentions a fabricated or weak hadith, with gentleness and leniency. As for jurisprudential rulings, the Imam should not be censured if he follows a particular school of thought or relates a recognized opinion, unless he welcomes and accepts advice, because jurisprudential differences are wide. It is advised not to discuss jurisprudential matters with Imams unless they are receptive to it, and there is no sin upon you if you do not offer advice due to the unacceptability of the advisee.