Like other Imams (A.S), Imam Hussein (A.S) also used to guide people through the book of Allah (S.W.T). The following beautiful incident has been recorded in Safinatul-Bihar:
Assaam bin Mustaliq was a man from Damascus who used to be a staunch enemy of the Ahlulbayt (A.S), particularly of Imam Ali bin Abi Talib (A.S). It is related that one day he came to Medina. As he entered the city gate, his eyes fell on Imam Hussein (A.S). Assaam bin Mustaliq was very disappointed and the hatred of Imam Ali bin Abi Talib (A.S) became evident in him. He approached Imam Hussein (A.S) and asked, "Are you the son of Ali bin Abi Talib?" Imam Hussein (A.S) replied in affirmative. When Assaam bin Mustaliq heard this, he began to abuse the Imam Hussein (A.S) and spoke bad words to him. Imam Hussein (A.S) calmly looked at him. When he was over, Imam Hussein (A.S) recited the following verses from the Noble Qur'an:
"Adopt tolerance, enjoin good and turn away from the ignorant. And if a prompting from Satan instigates you (to evil), then seek refuge with Allah. Verily He is all-Hearing, all-Knowing. Verily those who safeguard themselves (against evil) with full awareness of divine laws, when an evil thought from Satan assails them, they remember Allah, and lo! They see light. And their brethren plunge them deeper into error, so they do not slacken their efforts". (7:199-202)
Then Imam Hussein (A.S) said to Assaam bin Mustaliq, "You have been misled. We pray for our and your forgiveness from Allah (S.W.T). If you need our help, then we are willing to help. If you need our protection, then we are willing to defend you. And if you need our guidance, then we are willing to guide you".
When Assaam bin Mustaliq heard this, he was very ashamed of his rude remarks. Imam Hussain (A.S) continued, "From today onwards, there shall be no blame on you. May Allah (S.W.T) forgive you and He is the most Merciful". Then Imam Hussein (A.S) asked, "Are you from Damascus?" Assaam bin Mustaliq said, "Yes". Imam Hussein (A.S) said, "Whatever remarks you passed is of no importance to me, may Allah (S.W.T) protect us both. Without hesitation, present your needs to me. Whatever I offer you, I hope, will remove all misconceptions you have of me".
Assaam bin Mustaliq says, "When I heard this, I felt so ashamed but could not find any place to hide myself. Moreover, I wished the earth would tear apart and I would fall into it. After this encounter, there is no one on the face of this earth who is more beloved to me than Imam Hussain (A.S) and his fathers, Imam Ali bin Abi Talib (A.S)".
