The Nabī and the Rasūl

Abū Dharr came to the Messenger of Allah (peace be upon him) and asked him a question: qāla kam ʿiddatu al-anbiyāʾ? What is the total number of anbiyāʾ? The Messenger of Allah (peace be upon him) said: miʾatun wa ʿishrūna alfan, al-rusulu min dhālika thalāthu miʾatin wa khamsata ʿashara jamman ghafīrā. The Messenger of Allah (peace be upon him) said — what is the number of the anbiyāʾ? — 120,000^*; and the messengers among them are 315. So the anbiyāʾ of Allah (swt) are 120,000, and the messengers, al-rusul, are 315.

I'm translating nabī as prophet, and rasūl as messenger. So there are two different things: nabī and rasūl. Nabī: the plural of it is anbiyāʾ. Rasūl: the plural of it is rusul. So what is the difference between the nabī and the rasūl? What is the difference between the prophet and the messenger?

There are a few opinions of the ʿulamāʾ on this. One of them is that the rasūl is the nabī who is given a law. The rasūl is a nabī who is given a law; but the nabī who is not a rasūl is following the law of another rasūl. So every rasūl is a nabī, but not every nabī is a rasūl. Not every prophet is a messenger, but every messenger is a prophet. If a prophet is given a new law, then he becomes a rasūl and a nabī. If he is not given a new law, then he is a nabī — only a prophet.

An example of that, to make it a little bit clearer. Mūsā is a rasūl. Mūsā is a rasūl. Why? Because he was given the Torah. But Hārūn is not a rasūl; Hārūn is a nabī. Why? Because he is following the law of his brother: Hārūn is following the law of Mūsā. This is one difference that the ʿulamāʾ give between nabī and rasūl.