Once when Muawiyah had come to Medina he requested Imam Husayn (a.s) to go on the pulpit and give some admonitions. He thought the Imam would say something in praise of Muawiyah. Thus he went to the pulpit and after praise of Allah and blessings on the Prophet, he said, “People, know that we are that divine group which is going to be victorious over the deviated people. We are the progeny of the Prophet and his closest relatives. We are his purified and clean Ahl ul-Bayt and one of the two weighty things. The Messenger of Allah (S) has referred to us as the second book of Allah; it is the book having details about everything. Neither falsehood is before it or after it. We are the ones who know its interpretation and explanation. Its realities are hidden in our hearts. Our obedience is obligatory. Our obedience is connected to the obedience of Allah. Ask us whatever you want to ask about the Holy Quran. We are the shoreless oceans of sciences.”
The sermons and sayings of Imam Husayn (a.s) regarding divine sciences quoted in books like Biharul Anwar, Nurul Absar and Irshadul Quloob show eloquence and how beautifully he has solved the problems of religious sciences.
It is related from Jabir Ibn Abdullah Ansari that Imam Husayn (a.s) was an unsurpassed scholar of Quran, exegesis and traditions. When Muawiyah came to Medina in connection with the allegiance of Yazid, many companions of the Holy Prophet (S) went to meet him. The conversation turned to the topic of the most superior personality of the day in knowledge and virtues. Muawiyah wanted them to mention the name of Abdullah Ibn Umar but no one expressed this opinion. All of them unanimously said that, “We cannot find anyone better than Imam Husayn (a.s).” And why it shouldn’t be so? He was brought up by sucking the Prophet’s tongue. His chest is joined to the chest of the Prophet. He rode upon the shoulders of the Messenger of Allah (S).
Reference :Akhlaq al-A’imma, Morals & Manners of the Holy Imams