When letters filled two saddlebags, al-Husayn (‘a) wrote them one letter which he gave to Hani Ibn Hani al-Subay’i and Sa’id Ibn ‘Abdullah al-Hanafi. These were the last of his messengers.
Its text was:
In the Name of Allah, the Most Benevolent, the Most Merciful
“Hani and Sa’id brought me your letters, and they are the last to deliver them to me. I understand what you narrate, and the gist of most of your letters is: “We have no Imam; so, come to us, perhaps Allah will gather us with you on the path of guidance and righteousness.”
I have sent you my brother and cousin and the confidant of my Ahl al-Bayt and ordered him to write me with regard to your conditions, views and intentions.
So, if he writes me saying that your view is united with that of those of distinction and wisdom from among you and in agreement with what your messengers and letters state, I shall, by the Will of Allah, come to you very soon. By my life, an Imam is one who acts upon the Book [of Allah] and implements justice and follows the path of righteousness; he dedicates himself to follow Allah's Commandments, and peace be with you”.
(al-Tabari, Tarikh, Vol. 6, p. 198. al-Dinawari, Al Akhbar al-Tiwal, p. 238.)
He handed his letter to Muslim Ibn ‘Aqil saying:
“I am dispatching you to the people of Kufa, and Allah shall deal with you as He pleases. I wish that both of us should be in the status of the martyrs; so, proceed with Allah's blessing and help. Once you get there, stay with the most trustworthy of its people.”
(.al-Khawarizmi, Maqtal al-Husayn, Vol. 1, p. 196, chapter 10.)