جهاد الهوى إن لم يكن أعظم من جهاد الكفار فليس بدونه قال رجل للحسن البصري رحمه الله تعالى يا أبا سعيد أي الجهاد أفضل قال جهادك هواك وسمعت شيخنا يقول جهاد النفس والهوى أصل جهاد الكفار والمنافقين فإنه لا يقدر على جهادهم حتى يجاهد نفسه وهواه أولاً حتى يخرج اليهم
روضة المحبين ونزهة المشتاقين لإبن قيم الجوزية الباب التاسع والعشرون في ذم الهوى وما في مخالفته من نيل المنى
Jihad against passion, if not greater than jihad against the Disbelievers, is certainly not less than it. A certain man said to Hasan Al-Basri (may Allah Most High have mercy on him): Oh Abu Sa’id, What jihad is the best? He said: Your jihad against your passion. And I heard our sheikh say: Jihad of the self and against passion is the foundation for jihad against the disbelievers and hypocrites, for indeed one is not capable in jihad against them until one first engages in jihad against himself and his passion, so that he may then set out to them.
Ibn Qayyim, Rawda Al-muhibeen wa Nuzha Al-mushtaqeen [Garden of Lovers and Stroll of Those Who Yearn], The twenty-ninth section: regarding disapproval of passion and how it can be opposed in the attainment of destiny