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[mojtaba]

«بسم الله الرحمن الرحیم»
​

It is narrated in both Shia and Sunni authentic history books that,

When a Syrian saw Imam Hasan al-Mojtaba(peace be upon him)[the 2th Shia Imam and the grandson of Prophet Muhammad(sawaws) and son of Imam Ali(a.s.)] mounted on a horse, he began to abuse him[, because of propaganda of Mu'awiyah against Imam Ali(a.s.) and Ahlul Bayt(a.s.). See, Sonan Tirmidhi/ Minhaj As-Sunnah by Ibn Teymiyyah, v3,p15/ Sahih Muslim/ Fathul Mon'im Sharh Sahih Muslim by doctor Sheykh Musa Shahin Lashin(
فقال : ( ما منعك أن تسب أبا التراب ) ؟ معطوف علي محذوف ، والتقدير : امر معاويه سعدا أن يسب عليا ، فأمتنع ، فقال له : «ما منعك »ـ .)].

The Imam observed forbearance and did not react to his abusive language. When the fellow finished ranting to his heart's content the Imam said to him, “O gentleman! If you are in need, we can help you. If you have lost your way we can guide you. If you need a riding animal we can provide you with it. If you are hungry we can serve you food. If you require clothes we can offer them to you. If you are poor we can make you self-sufficient. If you are a visitor we can host you.”

Hearing these statements the Syrian began to weep and said, “Today I confess that you are the rightful caliph of God. I used to harbor great avarice against you and your respected father, now no one is dearer to me than you.”

One of the Shia sources,
Kashful Ghummah fi Marifatil 'A'immah, V.2, P.135 and 136.

One of the Sunni sources,
Tarikh Demashgh,Tarjuma Imam Al-Hasan, by Ibn Asakir, p.149.

 

[mojtaba]

It is narrated that Imam Sadiq(peace be upon him)[the 6th Shia Imam and a descendant of Prophet Muhammad(sawaws) and Imam Ali(as)] said to Unwan Al-basri,

"With regards to forbearance; if someone says to you ‘if you say one thing (of insult to me), you will hear ten things’ you should say to him: ‘if you say ten (insulting) things, you will not hear even one from me’.

If someone swears at you, say to him: ‘if you are truthful in what you say, then I ask Allah to forgive me, and if you are lying in what you say, then I ask Allah to forgive you’.

Finally, if someone promises you obscene language then promise him advice and care."

Source,
Bihar Al-Anwar, V.1, P.224.