Nahj al-Balāgha

Hadith 1433
imam-hasanahl-al-baytimam-husayndeath
ومن وصية له (عليه السلام) للحسن والحسين (عليهما السلام) لما ضربه ابن ملجم لعنه الله
For Imām al-Ḥasan and Imām al-Ḥusayn (peace be upon them) when (‘Abd ar-Raḥmān) Ibn Muljam (the curse of Allāh be upon him) struck him (fatally with a sword).
Source: al-Sharīf al-Raḍī