Is it permissible for an Imam of a mosque in Libya to study the Arabic language under someone who deviates from the methodology of the Salaf, due to his need for it in Da‘wah, knowing that the study is only one day a week and is limited to the Arabic language?

It is permissible to study linguistics under someone who deviates from the methodology of the Salaf, and evidence for this is that the Prophet (peace be upon him) ransomed some prisoners of Badr by having them teach the children of the Companions how to write. The considered deviation from the methodology of the Salaf lies in a fundamental principle or a legal rule. As for errors in minor details, they do not prevent benefiting from the one who deviates; rather, one refrains from imitating him in what he erred in. There must be justice in judging people and acknowledging the virtue of those who possess it. The Prophet (peace be upon him) encouraged honoring the elder and the scholar. Al-Dhahabi mentioned that rejecting a hadith (definition) from someone who has Shiite leanings without extremism would lead to the loss of a significant portion of prophetic traditions. Justice must be observed in judging scholars and those who differ, as Allah Almighty says: "And let not the hatred of a people prevent you from being just. Be just; that is nearer to righteousness."