Ibn Rajab reported: Ibrahim ibn Abi ‘Alqamah, may Allah have mercy on him, said to his people when they returned from a military expedition, “You have come from the lesser jihad, but you have not performed the greater jihad.” They said, “What is the greater jihad?” Ibrahim said, “It is the jihad of the heart.”
Al-Battal said, “Courage is to be patient for a time. This is the jihad against outward enemies, which is jihad against unbelievers. Likewise is the jihad against inward enemies, which is the jihad against the ego and lowly desires. Indeed, this is the greater of the two jihads.”
Source: Jāmi’ al-‘Ulūm wal-Ḥikam 1/489
عن ابن رجب قَالَ إِبْرَاهِيمُ بْنُ أَبِي عَلْقَمَةَ رحمه الله لِقَوْمٍ جَاءُوا مِنَ الْغَزْوِ قَدْ جِئْتُمْ مِنَ الْجِهَادِ الْأَصْغَرِ فَمَا فَعَلْتُمْ فِي الْجِهَادِ الْأَكْبَرِ قَالُوا وَمَا الْجِهَادُ الْأَكْبَرُ قَالَ جِهَادُ الْقَلْبِ
وَقَالَ الْبَطَّالُ الشَّجَاعَةُ صَبْرُ سَاعَةٍ وَهَذَا فِي جِهَادِ الْعَدُوِّ الظَّاهِرِ وَهُوَ جِهَادُ الْكُفَّارِ وَكَذَلِكَ جِهَادُ الْعَدُوِّ الْبَاطِنِ هُوَ جِهَادُ النَّفْسِ وَالْهَوَى فَإِنَّ جِهَادَهُمَا مِنْ أَعْظَمِ الْجِهَادِ
1/489 جامع العلوم والحكم الحديث التاسع عشر