The aim of sending the Holy Prophet (S) was to perfect the morals.
That is, the mission that did not reach the peak of perfection even after the arrival of 124000 messengers, it was done in theory and practice to such a level of perfection that now there was no more any need of a new prophet or messenger. This required extraordinary capability. That too in the land of Arabs, which was the cradle of ill manners. As if, shameless traits had hammered the final nail in the coffin of humanity. This severe necessity could neither be fulfilled by wealth and money nor by a military system or by the edge of the sword. This needed another type of power.
The verse: “Certainly you are upon the best morals,” (68:4) has revealed this secret and announced to the world that the aspect of Prophet's behavior is such that it transformed the Arab society completely.
It displayed such a miracle of human discourse that the world was spellbound. What actually happened may be understood in the words of Quran: People entered the fold of Islam in hordes. The good moral behavior of the Prophet of Islam had the most important role in this magnificent victory. Though Khadija's wealth served a great deal in helping the poor and deprived ones among the Muslims and the awe of Abu Talib afforded some security, but the thing that struck the hearts and minds of the polytheist and disbelieving Arabs was the good moral behavior of the Messenger of Islam. It was this that left an indelible mark on the hearts of ignorant Arabs and attracted the wild Arabs to the Prophet like a magnet pulls a needle. At that time Prophethood was veiled due to hidden wisdom when the Prophet started secret propagation and obtained confessions of his truthfulness from those who were deadly enemies of good morals, becoming well known as “The Truthful” and “The Trustworthy” among the Arabs.
The blood of human perfections had started running in this body known as Muhammad from the day it breathed its first in the atmosphere of water and clay. The teachings of Islamic morals to the people did not consist of mere oral admonitions, but it was accompanied by practical feats for every aspect. When those lacking any type of moral embellishments saw the flawless character of the Holy Prophet (S) they realized the degraded and shameful position of their own humanity. And on every occasion, their created nature was shaken with a deep yearning. The moral teachings that the Prophet imparted were the nourishment of the face of Islam and the life of its body. When these teachings were recorded on the pages of history and reached the different corners of the earth, and when with the Muslim travelers those teachings reached the people of other nations they were awakened abruptly from their slumber like a slow horse is spurred by the crack of the whip. it was an opportunity for the religions to compare that they make Islamic morals the criterion of comparing their differences. Those who did this realized very soon what is the difference between genuine and artificial pearls.