The heart becomes sick, as the body becomes sick, and its remedy is al-Tawbah (repentance) and protection [from transgression]. It becomes rusty as a mirror becomes rusty, and its clarity is obtained by remembrance. It becomes naked as the body becomes naked, and its beautification is al-Taqwa. It becomes hungry and thirsty as the body becomes hungry, and its food and drink are knowledge, love, dependence, repentance and servitude.
Ibn Qayyim Al-JawziyyaThe perfection of Tawheed is found when there remains nothing in the heart except Allaah
Ibn Qayyim Al-JawziyyaEverything that is loved, if it is not loved for His sake then this love is nothing but distress and punishment. Every action that is not performed for His sake then it is wasted and severed. Every heart that does not reach Him is wretched; veiled from achieving its success and happiness.
Ibn Qayyim Al-JawziyyaWhoever mocks his brother for a sin they repented from will not die till he himself falls into the same sin.
Ibn Qayyim Al-Jawziyya