Mālik Ibn Dīnār said:
I said to [Al-Ḥasan Al-Baṣrī], “What is the punishment of a scholar?” He replied, “The death of the heart.” I asked, “And what is the death of the heart?” He said, “Seeking the worldly life (Ad-Dunyā) with deeds of the Hereafter.”
Az-Zuhd by Aḥmad (1498)
Asceticism
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Amīr Al-Muʾminīn ʿUmar Ibn ʿAbd Al-ʿAzīz said:
Learn knowledge, for it is an adornment for the wealthy and assistance for the poor. I do not say that it is sought to gain wealth, but rather it calls to contentment (Qanāʿah).
Sīrat ʿUmar Ibn ʿAbd Al-ʿAzīz by Ibn ʿAbd Al-Ḥakam (p.151)
Knowledge Asceticism
ʿAlī ibn Abī Tālib said:
You will first be defeated at jihad with your hands, then jihad with your tongues, then jihad with your hearts. Any heart that does not recognize good nor denounce evil will be turned upside down.
Al-Muṣannaf by Ibn Abī Shaybah (38733)
Jihad
Al-Imām Sufyān Ibn ʿUyaynah Al-Makkī said:
The most ignorant a man can be is when he sees that he no longer needs knowledge.
An-nawādir wa an-nutaf by Abu as-Sheikh al-Asbahāni (190)
Knowledge