لَقَدْ أَرْسَلْنَا رُسُلَنَا بِالْبَيِّنَاتِ وَأَنزَلْنَا مَعَهُمُ الْكِتَابَ وَالْمِيزَانَ لِيَقُومَ النَّاسُ بِالْقِسْطِ ۖ وَأَنزَلْنَا الْحَدِيدَ فِيهِ بَأْسٌ شَدِيدٌ وَمَنَافِعُ لِلنَّاسِ وَلِيَعْلَمَ اللَّـهُ مَن يَنصُرُهُ وَرُسُلَهُ بِالْغَيْبِ ۚ إِنَّ اللَّـهَ قَوِيٌّ عَزِيزٌ
"We sent our messengers supported by clear proofs, and we sent down to them the scripture and the law, that the people may uphold justice. And we sent down the iron, wherein there is strength, and many benefits for the people. All this in order for GOD to distinguish those who would support Him and His messengers, on faith. GOD is Powerful, Almighty".[Quran;57:25]
In this brief sentence (verse) the whole essence of the mission of the Prophets bas been compressed, which one should clearly understand. It says that all the Messengers who came to the world from Allah, brought three things:
(1) Bayyenaat: manifest signs which clearly showed that they were really Allah’s Messengers, and were not impostors; convincing arguments which made it evident that what they were presenting as truth was really the truth, and what they condemned as falsehood was really falsehood. Clear instructions which told without any ambiguity what was the right way for the people in respect of beliefs, morals, acts of worship and dealings, which they should adopt, and what were the wrong ways which they should shun and avoid.
(2) Kitab: the Book which contained all the teachings required for the guidance of man so that people may turn to it for enlightenment.
(3) Mizan: the criterion of truth and falsehood which may precisely indicate, like a balance, the golden mean between two extremes in matters of thought, morals and dealings.
The object for which the Prophets were sent with these three things was that man’s conduct in the world and the system of human life, individually as well as collectively, should be established with justice. On the in hand, every man should precisely know the rights of God, the rights of his self and the rights of all those people with whom he may have to deal in any way, and should fulfill them faithfully. And on the other hand, the system of collective life should be built on such principles as should eliminate every kind of injustice from society, should safeguard every aspect of civilization and social life against extremism, should establish correct balance and equity in all spheres of collective life, so that all elements of society should receive their rights equitably and fulfill their obligations and duties responsibly.
In other words, the object of sending the prophets was to establish individual as well as collective justice. They wanted to establish justice in the personal life of each individual so as to bring about poise and equilibrium in his mind, his character, his conduct and his dealings. They also wanted to establish the whole system of human society on justice so that both the individual and the society should assist and cooperate with each other in their spiritual, moral and material well-being instead of being a hindrance and obstacle. [Tafheem ul Quran, Syed Abul A'la Modudi]