There is no doubt that it is obligatory on scholars wherever they are to propagate truth, promulgate the Sunnah, and teach people. They should not neglect doing that. Moreover, the people of knowledge should spread the truth through holding lessons in Masjids (mosques) in their vicinity, even if they are not appointed as Imams.
On Friday sermons, the Imam of every mosque should take care of his sermon and prepare it according to the needs of the people and concentrate on the points the audience does not know regarding religious affairs. Imams also have commitments to their neighbors and others. They should enjoin good, forbid evil, call to Islam, and teach the ignorant with kindness and wisdom. If scholars keep silent, do not give advice or guide people, the ignorant will speak out and misguide people.
Indeed, Allah does not take away (religious) knowledge by pulling it away from the (chests of) people. However, Allah takes the (religious) knowledge by taking away (inflicting death on) the scholars, till when none of the (religious learned men) remains, people will take as their leaders ignorant persons, who when consulted will give their verdict without knowledge. So they will go astray and will lead the people astray.
What has been mentioned above indicates that it is obligatory on the people of knowledge wherever they are in villages and cities, in tribes, in these countries, and so on to teach and guide people with what Allah (Glorified and Exalted be He) and His Messenger (peace be upon him) said. They should enquire about things that they do not know and refer to the Noble Qur'an, Sunnah, and the sayings of religious scholars.
A scholar should continue learning until he dies. He should learn so that he will know things that he does not know, refer to the sayings of religious scholars to make his verdict based on evidence, and teach people and call to Allah (Exalted be He) with insight.
Everyone needs to learn till he dies even if he was one of the Companions (may Allah be pleased with them). Everyone needs to acquire knowledge and comprehension of religion to know and learn. Thus, all Muslims are required to study and reflect on the Noble Qur'an, authentic Hadith and their commentaries. They should check the scholars' views to benefit from them, know what one does not know, and teach people at home, schools, institutes, universities, in mosques, on buses, planes, or everywhere, even in the cemetery if one attends a burial while people are still waiting. In such a case the person should remind them of Allah (Exalted be He) as the Prophet (peace be upon him) used to do.
To sum up, a scholar should take the opportunity at every suitable place or meeting and should not miss the chance to remind and teach people with good words and in a kind way. Scholars should make sure and beware of speaking in the Name of Allah without knowledge.