(O creatures!) Seek benefit from the sayings of Allah, be admonished of Allah and accept the advice of Allah because Allah has left no excuse for you by providing clear guidance, has put before you the plea and clarified for you what acts He likes and what acts He hates, so that you may follow the one and avoid the other. The Prophet of Allah used to say. "Paradise is surrounded by unpleasant things while Hell is surrounded by desires."
You should know that every obedience to Allah is unpleasant in appearance while every disobedience to Allah has the appearance of enjoyment. Allah may have mercy on the person who kept aloof from his desire and uprooted the appetite of his heart, because this heart has far-reaching aims and it goes on pursuing disobedience through desires.
You should know, O creatures of Allah, that a believer should be distrustful of his heart every morning and evening. He should always blame it (for shortcomings) and ask it to add to (its good acts). You should behave like those who have gone before you and the precedents in front of you. They left this world like a traveller and covered it as distance is covered.
And know that this Qur'an is an adviser who never deceives, a leader who never misleads and a narrator who never speaks a lie. No one will sit beside this Qur'an but that when he rises he will achieve one addition or one diminution - addition in his guidance or elimination in his (spiritual) blindness. You should also know that no one will need anything after (guidance from) the Qur'an and no one will be free from want before (guidance from) the Qur'an. 
Therefore, seek cure from it for your ailments and seek its assistance in your distresses. It contains a cure for the biggest diseases, namely unbelief, hypocrisy, revolt and misguidance. Pray to Allah through it and turn to Allah with its love. Do not ask the people through it. There is nothing like it through which the people should turn to Allah, the Sublime.
Know that it is an interceder and its intercession will be accepted. It is a speaker who is testified. For whoever the Qur'an intercedes on the Day of Judgement, its intercession for him would be accepted. He about whom the Qur'an speaks ill on the Day of Judgement shall testify to it. On the Day of Judgement an announcer will announce, "Beware. every sower of a crop is in distress except the sowers of the Qur'an." 
Therefore, you should be among the sowers of the Qur'an and its followers. Make it your guide towards Allah. Seek its advice for yourselves, do not trust your views against it. and regard your desires in the matter of the Qur'an as deceitful.
Action! action! Then (look at) the end; the end, and (remain) steadfast; steadfast. Thereafter (exercise) endurance, endurance, and piety, piety. You have an objective. Proceed towards your objective. You have a sign. Take guidance from your sign. Islam has an objective. Proceed towards its objective. Proceed towards Allah's by fulfilling His rights which He has enjoined upon you. He has clearly stated His demands for you. I am a witness for you and shall plead excuses on your behalf on the Day of Judgement.
Beware! What had been ordained has occurred and that which had been destined has come into play. I am speaking to you with the promise and pleas of Allah. Allah the Sublime, has said: 
You have said. "Our Lord is Allah." Then keep steadfast to His Book, to the way of His command and to the virtuous course of His worship. Thereafter do not go out of it, do not introduce innovations in it, and do not turn away from it, because those who go away from this course will be cut off from (the mercy of) Allah on the Day of Judgement.
Beware from destroying your manners and changing them, maintaining one tongue. A man should control his tongue because the tongue is obstinate with its master. By Allah, I do not find that fear of Allah benefits a man who practises it unless he controls his tongue. Certainly the tongue of a believer is at the back of his heart while the heart of a hypocrite is at the back of his tongue; because, when a believer intends to say anything, he thinks it over in his mind. If it is good he discloses it, but if it is bad he lets it remain concealed. While a hypocrite speaks whatever comes to his tongue, without knowing what is in his favour and what goes against him.
The Prophet of Allah - peace and blessing of Allah be upon him and his descendants - said: "The belief of a person cannot be firm unless his heart is firm, and his heart cannot be firm unless his tongue is firm." So whoever of you can manage to meet Allah, the Sublime, in such a position that his hands are unsmeared with the blood of Muslims and their property and his tongue is safe from exposing them, he should do so.
Know, O creatures of Allah, that a believer should regard lawful this year what he regarded lawful in the previous year, and should consider unlawful this year what he considered unlawful in the previous year. Certainly people's innovation cannot make lawful for you what has been declared unlawful; rather, lawful is that which Allah has made lawful and unlawful is that which Allah has made unlawful. You have already tested the matters and tried them; you have been preached by those before you. Illustrations have been drawn for you and you have been called to clear fact. Only a deaf man can remain deaf to all this, and only a blind man can remain blind to all this.
Allah the Glorified, has not counselled anyone on the lines of this Qur'an, for it is the strong rope of Allah and His trustworthy means. It contains the blossoming of the heart and springs of knowledge. For the heart there is no other gloss than the Qur'an although those who remembered it have passed away while those who forgot or pretended to have forgotten it have remained. If you see any good give your support to it, but if you see evil evade it, because the Messenger of Allah used to say: "O son of Adam, do good and evade evil; by doing so you will be treading correctly."
Know that injustice is of three kinds - one, the injustice that will not be forgiven, another, that will not be left unquestioned, and another that will be forgiven without being questioned. The injustice that will not be forgiven is duality of Allah. Allah has said:
 Verily Allah forgiveth not that (anything) be associated with Him ... (Qur'an, 4:48,116). 
The injustice that will be forgiven is the injustice a man does to himself by committing small sins; and the injustice that will not be left unquestioned is the injustice of men against other men. The retribution in such a case is severe. It is not wounding with knives, nor striking with whips, but it is so severe that all these things are small against it. You should therefore avoid change in the matter of Allah's religion for your unity in respect of a right which you dislike is better than your scattering away in respect of a wrong that you like. Certainly, Allah the Glorified has not given any person, whether among the dead or among those who survive, any good from separation.
O people, blessed is the man whose own shortcomings keep him away from (looking into) the shortcomings of others, and also blessed is the man who is confined to his house, eats his meal, buries himself in obeying his Allah. and weeps over his sins, so that he is engaged in himself and people are in safety from him.
(2) al-Kulayni, Usul al-Kafi, II, 443;
(3) al-Barqi, al-Mahasin, 6;
(4) al-Saduq, al-'Amali, 153;
(6) al-Harrani, Tuhaf, 71.