You have been expelled for the sake of the best people. You enjoin what is right and forbid what is wrong, and believe in Allah. (Surat al-Imran, 110)
Muslims are the greatest nation and Muhammadan Ummah is the best Ummah - this has been clearly stated in various hadiths. This is clearly stated or implied in various verses of the Qur'an.
In the above verse, it has been declared as the best and the reason has been mentioned in the hint. That is to say, you are of the best opinion because you have done good deeds and not bad deeds. The commentators have written that this verse (Amr Bil Ma'roof and Nahi Anil Munkar) has been mentioned before Iman but Iman is the root of all worship; No good deed is acceptable without faith. The implication of this is that there have been other ummahs and partners in the past regarding faith; But the only feature (Amr Bil Ma'roof and Nahi Anil Munkar) that distinguishes Muhammad's Ummah from all the Prophets' followers is the special feature of uniqueness and since no good deed is acceptable without Iman, he immediately mentioned the truth. Otherwise the real purpose of this verse (Amal Maruf and Nahi Anil Munkar) is to be mentioned, and since Ohai is the subject of discussion here, it has been mentioned earlier.
To be a special sign of uniqueness for this Ummah means to do this with special importance; Just preaching something through movement will not be enough. For, such a short preaching was found in the previous ummah. Such as (Faamma Nasu Ma Yukkiru Bihi) etc. are mentioned in the verse. So I think it is a characteristic of this ummah to be engaged in this work with special importance, like other day's work.
From this verse we have learned that we, the last ummah, have to work harder and harder to call people to the truth, which is the command to do good and forbid evil.