Shaykh Rabīʻ ibn Hādī al-Madkhalī:

We must return to Allāh ﷻ, return to the truth and we must go back to the affair of having love and hate for the sake of Allāh. 

Study this affair from Khalq Afʿāl al ʿIbād by Imām al-Bukhārī and look at the stance of pious predecessors towards the people of innovation . Likewise, al-ʿItiṣām by ash-Shātibī, in fact leave that aside. as-Sunnah by ʿAbdullāh ibn Imām Aḥmad, Ash-Sharīʿah by Imām al-Ājury Sharh Uṣūl al-I’tiqād Ahl as-Sunnah by Imām al-Lālikā’ī. [and] the two al-Ibānāhs by ibn Baṭṭah.

The methodology of righteous predecessors will not be understood by anyone who does not study the aforementioned books, and especially the affair of love and hate for the sake of Allāh ﷻ. The enemies of Salafīyyah have tried to abolish the affair of loving and hating for the sake of Allāh. They tried to rub it out of the Salafī methodology. So let us bring back this affair and study and preserve it.