This is a very important branch of Islam every thing that has been ordered by god is called maaru’f i.e.; good, For example prayers, fasting, to pay the Zakat and Khums and to establish fundamentals of Islam; as is everything recommended by Islam like to feed and welcome guest, to teach good behavior and mould pleasant characters.
It is obligatory to enjoin one to do good the first time, it is optional the second time.
Enjoining good deeds is obligatory upon four conditions:

1. The enjoiner himself knows what is good and what is bad;
2. He hopes that his advice will be followed;
3. The person whom he wants to advis�, iw persisting in not doing that good work.
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4. The enjoiner knows that he won’t suffer any harm by his"enjoining goo.
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"B5T when the basic faith of tie Muslims is in fanfer or tenet of Islae is being underminmc (fgr example; �hen`a country tries to changu a people’s belie& or wants To encoUrage drinking and gambling(at gatherings) then it is obligation$upon everyone (to enjoin go/d and advise against what is!forbidden even though by so doing, one may come to harm; like our holy Imams did in similar circumstances.
“And form among you there should be a group who invite good and enjoin what is right 0 and forbid the wrong; and the only shall be 3uccessful. * "
� (Hly Qur’an 3; 103)
Exhorting others to be virtuous is one of the most important duties of a Muslim. A society can progress in right direction so long as there are people in it who knows the right path and who are willing to show it to others. Otherwise, the whole caravan may perish in a beastly jungle of anarchy and infidelity.
But how that exhortation is to be carried out Allah says in the Qur’an will ask: “why do you speak of a thing which you yourself do it not ?”So this duty of inviting others to righteousness compels a man to be righteous himself.
And how that exhortation is to be carried out Allah says in the Qur’an:
“Call unto the way of thy lord with wisdom and kind preaching; and argue with them in the best manner”. (Holy Qur’an 16;125).
This was the method used by the Holy Prophet of Islam and his true followers to spread the message of Islam and to teach people the real significance of religion.
An interesting story is told of an old man in Medina who was engaged in ablution (Wuzu) for his prayers. Imam Hasan (a.s) and Imam Husain(a.s) (the grand sons of the Holy Prophet and of tender age at that time) realized that the man does not know the correct method of ablution. They wanted to correct him; but at the same time did not like to offend his feelings. So they approached him and told: “We are two brothers and we want you to be the judge between us as whose ablution is correct.” When the old man agreed, the children proceeded to perform their ablution, in the most perfect way. The old man was watching them intently. He had to; he was to judge. Soon it dawned upon him that the children, in their kind and gentlemanner, were teaching him. He exclaimed: “You both are correct. It was I who was wrong.”
The old man learnt his lesson. But this episode will continue to show the preachers also how to preach.