The people of knowledge and faith, who have been granted the Quran and faith, are as Allah Most High describes:

“Allah is the Light of the heavens and the earth. The likeness of His light is that of a niche containing a lamp; the lamp is within glass, and the glass is like a brilliant star, lit from a blessed olive tree, neither eastern nor western, whose oil would almost glow even if no fire touched it. Light upon light. Allah guides to His light whom He wills. Allah sets forth examples for people, and Allah knows all things. (35)” [al-Nūr 35]

This light is the light of both faith and the Quran, as Allah Most High says:

“And thus We have revealed to you a spirit by Our command. You did not know what the Scripture was, nor what faith was, but We made it a light by which We guide whom We will of Our servants. And indeed, you guide to a straight path (52)—the path of Allah, to whom belongs whatever is in the heavens and whatever is on earth. Surely, to Allah all matters return. (53)” [al-Shūrā 52–53]

This is how the early generations—the Companions, the Successors, and others, may Allah be pleased with them—explained it, as related by ʿAbd ibn Humayd: ʿAbd Allāh ibn Yūsuf narrated to us, from Abū