Tafsir of Al-Ahzab 33:45-46

{A witness} over those to whom you were sent, regarding their denial or their belief. That is: your word is accepted by God for them and against them, just as the testimony of a just witness is accepted in judgment.

If you ask: How could he be a witness at the time of being sent, when witnessing only occurs at the time of bearing or delivering testimony? I say: It is [a reference to] what is destined to happen, like saying "tomorrow's prey."

If you ask: It is understood from the statement "We have sent you as a caller" that he is permitted to call; so what is the benefit of saying {by His permission}? I say: It does not mean literal permission. Rather, "permission" is used metaphorically to mean facilitation and ease. Entering into the right of an owner is difficult, but if permission is found, it becomes easy. Since permission facilitates what is otherwise difficult, it is used in that context. Calling the people of polytheism and ignorance to monotheism and the laws is an extremely difficult and arduous task. Thus, it was said "by His permission" to signal that the matter is difficult and cannot be accomplished or sustained unless God facilitates and eases it. From this is the saying regarding a stingy person: "He is not permitted to spend," meaning spending is not made easy for him because it is burdensome and falls under the category of the impossible.

{And a lamp giving light} He cleared the darkness of polytheism with him, and the misguided were guided by him, just as the darkness of the night is cleared by a luminous lamp and one is guided by it. Or, God extended the light of insights with the light of his prophethood, just as the light of sight is extended by the light of a lamp. It is described as "giving light" because some lamps do not shine if their oil is low or their wick is thin.

In the speech of some: "Three things cause exhaustion: a slow messenger, a lamp that does not shine, and a table waiting for someone to arrive." Someone was asked about what is desolate, and he said: "A covering darkness and a dim lamp."

It is also said: [The verse means] "And as a luminous lamp," or "And following a luminous lamp." Under this interpretation, it is permissible to connect it to the kaf (the 'you') in {We have sent you}.

{And give good tidings to the believers that they will have from Allah a great bounty.}