What is the ruling of Islam concerning Da'wah?

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

Allaah Says (what means): {And let there be [arising] from you a nation inviting to [all that is] good, enjoining what is right and forbidding what is wrong, and those will be the successful.}[Quran 3:104]

The scholars of Tafseer have different opinions in their commentary on this verse.

The predominant opinion is that Da’wah is an obligation upon each and every person in addition to being a communal obligation. Ibn Katheer clarified in his commentary on the previously-mentioned verse [Quran 3:104] that there must be a group of Muslims specified for undertaking the responsibility of performing Da‘wah. He added, however, that Da’wah remains an obligation on every Muslim individual, each according to his own ability and knowledge. This is supported by the Hadeeth on the authority of Abu Hurayrah where the Prophet, sallallaahu ‘alayhi wa sallam, ordered the one who sees an evil to change it physically with his hand if he was able to do so. If he could not, he should change it by his tongue (by advising and/or condemning), and finally by (detesting it with) his heart, and he informed that this is the weakest level of faith. [Muslim]

Allaah Knows best.