Hazrat Mufti Ebrahim Salejee (Daamat Barakaatuhu) mentioned:
Nabi (sallallahu ‘alaihi wasallam) has been likened to a brilliant lamp (siraajam-muneera) in the Quraan instead of a shining sun. Various reasons have been given. Among them is that a lamp is something that is accessible and which man is familiar with. This was evident in the life of Nabi (sallallahu ‘alaihi wasallam). Another reason is that one lamp can light up thousands of other lamps whereas this is not the case with the sun.
Hazrat Mufti Muhammad Shafee’ Saahib (rahmatullahi ‘alaih) explains that the manner in setting alight our lamps through the lamp of Nabi (sallallahu ‘alaihi wasallam) is by emulating the sunnat of Nabi (sallallahu ‘alaihi wasallam) and sending abundant durood upon our beloved Rasul (sallallahu ‘alaihi wasallam).