The Sunnah vs. What People Do

It is reported that:

ʿAbdullāh b. Al-Ḥasan used to often sit with Rabīʿah. One day they were revising and studying various practices from the Sunnah when a man in the gathering said, “[But] this is not what is practiced [by the people].” ʿAbdullah said, “So if the ignorant become so numerous that they become the rulers and judges, will they then be a proof over the Sunnah?” Rabīʿah said, “I bear witness that these are the words of the sons of the Prophets.”

Al-Khaṭīb Al-Baghdādī, Al-Faqīh wa Al-Mutafaqqiharticle 384.