Then Allah sent Muhammad (S) as a witness, giver of good tidings and warner, the best in the universe as a child and the most chaste as a grown up man, the purest of the purified in conduct, the most generous of those who are approached for generosity.
This world did not appear sweet to you in its pleasures and you did not secure milk from its udders except after having met it when its nose-rein was trailing and its leather girth was loose. For certain people its unlawful items were like bent branches (laden with fruit) while its lawful items were far away, not available. 
By Allah, you would find it like a long shade upto a fixed time. So the earth is with you without let or hindrance and your hands in it are extended while the hands of the leaders are held away from you. Your swords are hanging over them while their swords are held away from you.
Beware that for every blood (that is shed) there is an avenger and for every right there is a claimant. The avenger for our blood is like the judge for his own claim, and it is Allah who is such that if one seeks Him, then He does not disappoint him, and one who runs away from Him cannot escape Him. I swear by Allah, O Banu Umayyah, shortly you will see it (i.e. your possession) in the hands of others and in the house of your enemy. Know that the best looking eye is that whose sight catches virtue and know that the best hearing ear is that which hears good advice and accepts it.
O people! Secure light from the flame of lamps of the preacher who follows what he preaches and draw water from the spring which has been cleaned of dirt.
O creatures of Allah, do not rely on your ignorance, do not be obedient to your desires, because he who stays at this place is like one who stays on the brink of a bank undermined by water carrying ruin on his back from one portion to the other following his opinion which he changes (one after the other). He wants to make adhere what cannot adhere and to bring together what cannot keep together. So fear Allah and do not place your complaints before him who cannot redress your grievance, nor undo with his opinion what has been made obligatory for you.
Certainly, there is no obligation on the Imam except what has been devolved on him from Allah, namely to convey warnings, to exert in good advice, to revive the sunnah, to enforce penalties on those liable to them and to issue shares to the deserving. So hasten towards knowledge before its vegetation dries up and before you turn yourselves away from seeking knowledge from those who have it. Desist others from the unlawful and abstain from it yourself, because you have been commanded to abstain (yourself) before abstaining (others).
(1) Al-Mufid, al-'Irshad, 160;