Arguing with a Scholar or an Ignoramus

Yūnus reports: Maymūn b. Mihrān once wrote to me saying:

Beware of dispute and argumentation about the religion, and do not argue with a scholar nor an ignoramus. As for the scholar, he will withhold his knowledge from you, and will not be concerned with what you do. As for the ignorant person, he will only cause roughness in your heart and he will not obey you [anyway].

Al-Dārimī, Al-Sunan no. 302.