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
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Shaykh Al-Islām Ibn Taymiyyah said:
The one who refutes the people of innovation is a mujāhid, to the extent that Yahyā ibn Yahyā used to say: “Defending the Sunnah is better than jihād.”
Majmūʿ Al-Fatāwā (4/13)
Sunnah Jihad
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
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