Nahj al-Balāgha
Hadith 911ومن خطبة له (عليه السلام) يحمد اللّه ويثني على نبيه ويعظ بالتقوى
Importance of fear of Allāh, desolateless of the grave, and about the death of the lover of Ahlu’l-bayt being like that of a martyr