As the verse: "So call and go straight as you have been ordered to…" (Surat ash-Shura: 15) makes clear, the Prophet Muhammad (saas) was the last prophet charged with warning mankind. Like all the other messengers, the Prophet (saas) called people to the true path, to have faith in Allah, to live for the hereafter and to exercise good morality. The methods he employed, the way he explained things, and the style he used must remain examples for all Muslims, and when a Muslim invites people to the religion he must speak and behave in the manner of the Prophet (saas).
This is how the Qur'an reveals that the Prophet (saas) was commanded to say that he had come to warn mankind:
Say: "This is my way. I call to Allah with inner sight, I and all who follow me. Glory be to Allah! I am not one of the idolators!" (Surah Yusuf: 108)
The Prophet (saas) did all that he could and more to warn people, and extended great effort to address as many people as he could. One verse reveals:
Say: "What thing is greatest as a witness?" Say: "Allah. He is Witness between me and you. This Qur'an has been revealed to me so that I may warn you by it, and anyone else it reaches. Do you then bear witness that there are other gods together with Allah?" Say: "I do not bear witness." Say: "He is only One God, and I am free of all you associate with Him." (Surat al-An'am: 19)
By communicating the message of the Qur'an, the Prophet (saas) completely abolished the corrupt religions that the polytheists had inherited from their ancestors, for which reason he met with much resistance. Yet, he abided by Allah's command and took no notice of their oppression and animosity. Allah commands the Prophet (saas) thus in one verse:
Proclaim what you have been ordered to and turn away from the idolators. We are enough for you against the mockers. (Surat al-Hijr: 94-95)
Muslims in our own time too must explain the morality of the Qur'an to people, ignoring any lack of approval and whatever anyone might say to oppose them. They must not fear "the blame of any blamer," as the Prophet (saas) did. That is a sign of morality and godliness that will be rewarded with Paradise. The Prophet (saas) commanded Muslims to abide by that Sunnah in these words, "Convey my teaching to the people even if it were a single sentence."35