Musannaf Ibn Abi Shayba 37:470

Abu Mu’awiyah narrated to us, from al-A’mash, from Qays ibn Rashid, from Abu Juhayfah, from Ali, who said: "Indeed, the first thing you will be overcome in regarding Jihad is Jihad with your hands, then Jihad with your tongues, then Jihad with your hearts. So, whoever has a heart that does not recognize the good and does not reject the evil, it is overturned, such that its top is made its bottom."