(O Muhammad!) We have sent you to be a real blessing for the people of the world. Say to them, “That which is revealed to me is this: Your Deity is One Deity only. Will you, then, surrender to Him?” If even then, they turn away from it, tell them plainly, “I have warned you openly; now I do not know whether that thing with which you are being threatened is near at hand or far off. You should, however, note it well that Allah has the knowledge of what is uttered aloud and also of what you talk about secretly.
(A-Qur'an – 21:107-10)
The verse (21:107) can also be translated as: “We have sent you only as a blessing for the people of the world”. In both cases it will mean that the appointment of the Holy Prophet (blessings and peace of Allah be upon him) is indeed a blessing and mercy of Allah to the whole world. This is because he aroused the neglectful world from its heedlessness and gave it the knowledge of the criterion between truth and falsehood, and warned it very clearly of both the ways of salvation and ruin. This fact has been stated here 'to tell the disbelievers of Makkah that they were quite wrong in their estimate of the Holy Prophet that he was an affliction and distress for them because they said, “This man has sown seeds of discord among our clans and separated near relatives from each other.” They have been told here, “O foolish people, you are wrong to presume that he is an affliction for you; but he is in reality a blessing and mercy of Allah for you.” The expression “I do not know whether that thing with which you are being threatened is near at hand or far off” means: “I do not know the time and the form of the punishment of Allah for your rejection of the Message. It may come at any time in any shape.”