Letter to Imam al-Husayn and His reply to the people of Kufa-680 CE

Now, I send my brother, my cousin and a reliable person in my relatives to you. If he writes that the opinions of most of you and your wise and elder ones is in agreement with what your messengers inform about and I read in your letters, I will soon come to you by the will of God; for I swear by my soul that Imam (a) is not anyone but one who rules according to the Book of God, rises to justice, observes the religion of truth and commits himself to what God has said and ordered.