The speech is now directed to all human beings, the previous heavenly messages have come to different separate regions and peoples, where there were no ways of communication or transportation, so no people know anything about another, one prophet descended here and another there, where the conditions are different and diseases are multiple, until the message of Islam has descended to the Prophet Muhammad (saws) to all people because humanity has come to its maturity and the scientific development has started, so the whole world has become as one spot, and the transportation routes are available between its parts, so the speech was directed to all people, as if Islam preceded the world.
(… قَدْ جَاءَكُم بُرْهَانٌ …) (…there has come to you a conclusive proof..): The conclusive proof is the miraculous indicative of the truthfulness of the one who has a Message from Allah (swt), so every Prophet came with a miracle indicating the sincerity of his message from Allah (swt), for example: For Noah (PBUH) it was the ark which was the miracle that saved those who got in it and drowned everyone who did not board it, Saleh’s (PBUH) miracle was the she-camel, Abraham (PBUH) was not burned by fire when he was thrown into it because Allah (swt) made it lose its characteristic, this was a miracle. Moses (PBUH), one of his miracles was the stick where he used to hit the stone and it exploded, and he hit the sea and it split open. Hence, the Messengers always came with a miracle to support their messages. Jesus (PBUH) used to revive the dead with the permission of Allah (swt), heal the blind and the lepers, and heal the sick. They all came with the proof and with them came the method: The Bible, The Torah, The Scriptures, The Psalms. These miracles ended at the death of the Prophet who was present at that time. As for the Messenger Muhammad (saws), the last Prophet, who said:
“There is no Prophet after me.”
So that he comes with an everlasting miracle; the Holy Quran.
( وَأَنزَلْنَا إِلَيْكُمْ نُورًا مُّبِينًا… ) (and We have sent down to you a clear light …): It is the light that shows the way to those who walk in darkness, In the Holy Quran we find in the miracle, evidence and proof, and it is immortal till the last day. Allah (swt) says:
إِنَّا نَحْنُ نَزَّلْنَا الذِّكْرَ وَإِنَّا لَهُ لَحَافِظُونَ
(Indeed, it is We who sent down the Qur’an and indeed, We will be its guardian.) (Al-Hijr: 9)
 Sahih al-Bukhari: The Book of Prophets, Chapter of: What is reported about the Children of Israel, Hadith No. 3268.