Learning from history, al-Mahdi
Nahj al-Balāgha|Volume 1|Book 1|Chapter 182
قال: ثُمَّ ضَرَبَ (عليه السلام) بِيَدِهِ عَلَى لِحْيَتِهِ الشَّرِيفَةِ الْكَرِيمَةِ، فَأَطَالَ الْبُكَاءَ، ثُمَّ قَالَ (عليه السلام):
Then Amīr al-mu’minīn wiped his hand over his auspicious, honoured beard and wept for a long time, then he continued: