"It is He Who sent forth among the unlettered an apostle of...
"It is He Who sent forth among the unlettered an apostle of their own to recite to them His revelations, to purify them, and to instruct them in the scriptures and wisdom, - (62:2) From this verse of the Holy Quran, we arrive at a conclusion that there were four main assignments of the prophet. No other person except a Divine agent is capable to do these works. 1 - To guide the mankind to the right path.
2 - To inform the people about the unseen and hidden realities which they can never know or perceive by themselves. 3 - To purify their souls and to develop their morals of Divine standard. 4 - To certify the actions of people on the day of judgment. 1st assignment of the Prophet - to guide the people. This was the first and the main duty of all the prophets.
To do this work efficiently and adequately, Allah Taala gave the prophets, both theoretical book [core concepts] and Practical book [ Shariah - complete codes of ideal life]. All actions and activities of the Prophets were totally according to the Divine Will. In this way the life of the Prophet itself was an open book. All Prophets taught their respective nations all essential things that are necessar y for a meaningful life in this world and for the ultimate success of the eternal world.
2nd assignment - To inform the people about the hidden and unseen realities. This was the second important work of the Prophets. There are many facts and truths which are totally beyond the human reach. Man can never know them unless a reliable person from God tells and explains these facts. 3rd assignment - to purify the souls and to develop high morals. This is the third important duty of the Prophets.
Quran declares the prophethood as a great favor of Allah Taala to mankind and a source of His unlimited mercy. "O mankind: there has come to you a direction from your Lord for the (to cure disease) heart - and for those who believe, a guidance and a mercy." (10:57) 4th assignment - to certify the actions of the people on the Day of Judgment. Quran informs us that on the day of Judgment, the Prophets and their true successors, Imam, will be asked to give full reports of their nation.
"One day We shall call together all human beings with their (respective) Imams: those who are given their record in their right hand will read it (with pleasure), and they will not be dealt with unjustly in the least." (17:71) Characteristic features of Prophets.