The Era of the Companions:
The Quran is the final revelation sent by Allah to Prophet Muhammad (may Allah exalt his mention). It is an eternal miracle that grows in clarity and strength with time and each new scientific discovery. It was revealed over nearly twenty-three years, during which the Prophet taught it and explained it to his companions, may Allah be pleased with them. He sallallaahu' alayhi wa sallam also answered all of their questions and did not die before completely delivering the message of the Quran, making it clearly understood.
At the same time, the Companions, may Allah be pleased with them, were very keen to memorise, understand and practice it. Due to their mastery of Arabic, the purity of their minds and hearts, and because they had witnessed the Quran being revealed under many circumstances and in response to diverse events, they were able to accumulate much understanding and knowledge of the Quran.
Some of them actually mastered its knowledge. Abdullaah bin Mas'ood, may Allah be pleased with him, was one of those who realised this great achievement. He described his knowledge of the Quran by saying: “I swear by Allah that there is not a verse of the Quran except that I know where and why it was revealed, and if I knew of anyone who knows the Book of Allah more than I do, I would travel to him.” [Al-Bukhari]
Other Companions devoted all of their lives to the Quran. Abdullaah bin 'Umar, may Allah be pleased with him, for example, was reported by Imaam Maalik in ‘Al-Muwatta’ as having spent eight consecutive years completely memorising and learning Soorah (chapter) Al-Baqarah (the second Quranic chapter).
It was also reported that the Companions, may Allah be pleased with them, used to say, “It is considered to be a great thing that one of us learns the Soorahs Al-Baqarah and Aal 'Imraan (The second and third chapters).” And that: “They used to learn the Quran from the Prophet ten verses at a time, and that they would not go beyond them until they had learned all possible knowledge and actions in them and applied them.”
This great knowledge was not all written down as text, except for what was written down by some Companions, may Allah be pleased with them. The reason was that the basic process of teaching and learning in those times was the oral tradition. Only the Quran itself and those Companions' writings were received in written format by the next generation of Muslims.
However, many of the Companions, may Allah be pleased with them, were known for their excellent knowledge and understanding of the Quran. People like 'Uthmaan, Ali, Zayd, Ubay, Ibn Mas'ood, Ibn 'Abbaas and Ibn 'Umar, may Allah be pleased with them, as well as others, had many brilliant and inspired students, such as Mujaahid, Qataadah and 'Ataa', may Allah have mercy on them, who then conveyed that knowledge to the rest of Ummah (Muslim community) as the practice of writing down knowledge became widespread.
The Companions’ circles of teaching were attended by hundreds of students. As those students went back home, they taught others the same knowledge as they had learned. Within a short period of time, the Companions’ knowledge, was spread across the vast Muslim lands.
What is so remarkable is that after writing became popular, the pieces of knowledge collected from different scholars who had never seen or known one another were found to be the same and, therefore, supported one another – showing consistency in the knowledge and the guidance of Islam.
To this day and forever, no other Ummah or religion can claim similarity to this unique feature of Islam.