Tafsir of An-Nisa' 4:136

"O you who have believed..." An address to the Muslims. The meaning of "have believed" is: remain firm in faith, persist in it, and increase in it.

"...and the Book which He sent down before..." The intent here is the genus of the Books sent down to the prophets before him. The evidence for this is His saying: "and His Books." It is also recited as "His Book" (wa-kitābihi), intending the genus. It is also recited as nazzala (He sent down) and unzila (it was sent down) in the active voice.

It is said: The address is to the People of the Scripture, because they believed in some books and messengers while disbelieving in others. It is narrated that this was revealed regarding ‘Abd Allāh ibn Salām, Asad and Usayd (the sons of Ka‘b), Tha‘labah ibn Qays, Salām (the nephew of ‘Abd Allāh ibn Salām), Salamah (his nephew), and Yāmīn ibn Yāmīn. They came to the Messenger of Allah (ﷺ) and said: "O Messenger of Allah, we believe in you, your Book, Moses, the Torah, and ‘Uzayr, but we disbelieve in all other books and messengers." The Prophet (ﷺ) replied: "Rather, believe in Allah, His Messenger Muhammad, His Book the Qur’an, and every book that came before it." They said: "We will not do that." Then this verse was revealed, and they all believed. (Ibn Hajar noted in Takhrij al-Kashshaf (1/576) that al-Tha‘labi mentioned this from the narration of al-Kalbi, from Abū Ṣāliḥ, from Ibn ‘Abbās).

It is also said: It is addressed to the hypocrites, as if to say: "O you who have believed hypocritically, believe sincerely."

If you ask: How is it said to the People of the Scripture, "and the Book which He sent down before," when they were already believers in the Torah and the Gospel? I reply: They only believed in those two specifically, and they were not believers in all the books that were sent down. Thus, they were commanded to believe in the entire genus. Furthermore, their belief in some books does not constitute valid belief in them, because the path to believing in a book is through the miracle, and miracles are not exclusive to one book over another. If their belief in what they accepted had been due to the miracle, they would have believed in all of them. Since they believed in only some, it is known that they did not consider the miracle; therefore, their belief was not true belief.

This is what the Almighty intended in His saying: "And they say, 'We believe in some and disbelieve in some,' and wish to adopt a way in between - those are the disbelievers, truly" (An-Nisa: 150-151).

If you ask: Why is it said "sent down to His Messenger" (nazzala) and "sent down before" (unzila)? I reply: Because the Qur’an was sent down in parts and stages over twenty years, unlike the books before it.

"And whoever disbelieves in Allah..." The meaning is: whoever disbelieves in any of that...

"...has certainly gone far astray." Because disbelief in a part of it is disbelief in the whole of it. Do you not see how He preceded it with the command to believe in all of it?