Imām Ibn al-Jawzī (d. 597/1201) summarized the scholars' opinions in his book "Zād al-Masīr" as follows: 

1. It refers to what has been revealed (of the Qurʾān). [Ibn Masʿūd, Ibn ʿAbbās] 
2. It refers to what is in their possession, meaning that if they conceal the description of the Prophet Muḥammad (ﷺ) while they possess it, they would be guilty of disbelieving in it. [Mentioned by al-Zajjāj]

What does the pronoun "it" refer to in "don't be the first to disbelieve in *it*"?

Imām Ibn al-Jawzī (d. 597/1201) summarized the scholars' opinions in his book *Zād al-Masīr* as follows: 

1. It refers to the worldly gains they would make.
2. It refers to maintaing their leadership over the people. 
3. It refers to taking payment for teaching the religion.

What does "selling God's verses for a small price" refer to?