From the benefits of Ash Shaykh Abdul Hameed Az-Zu’akari Al Hajooree:
It is befitting for every Muslim who knows something from the book of Allah or from the Sunnah of the messenger of Allah صلى الله عليه و سلم that he be a caller to Allah. It is not a condition in regards to Ad Dawah (calling) that he stand up and be one who gives sermons or write a book. This is considered from calling and from the greatest of it, but be one who commands the good and forbids the evil in accordance to your capability.
“Whosoever of you sees an evil, let him change it with his hand; and if he is not able to do so, then [let him change it] with his tongue; and if he is not able to do so, then with his heart — and that is the weakest of faith”
Majid Jawed Al-Afghanee