All praise is due to Allah the Lord of the worlds. Peace and blessings of Allah to His Messenger Muhammad, his family and followers until the end of the World.
The foundation
In Islam enjoining good and forbidding evil is one of the duties of a Muslim. Allah said:
You [true believers in Islamic Monotheism, and real followers of Prophet Muhammad SAW and his Sunnah (legal ways, etc.)] are the best of peoples ever raised up for mankind; you enjoin Al-Ma’ruf (i.e. Islamic Monotheism and all that Islam has ordained) and forbid Al-Munkar (polytheism, disbelief and all that Islam has forbidden), and you believe in Allah. And had the people of the Scripture (Jews and Christians) believed, it would have been better for them; among them are some who have faith, but most of them are Al-Fasiqun (disobedient to Allah - and rebellious against Allah's Command).
Al Imran (3) 110[1]
In another verse,
Let there arise out of you a group of people inviting to all that is good (Islam), enjoining Al-Ma’ruf (i.e. Islamic Monotheism and all that Islam orders one to do) and forbidding Al-Munkar (polytheism and disbelief and all that Islam has forbidden). And it is they who are the successful.
Al Imrân (03) Verse 104.
In his Tafsir, Ibn Kathir[2] said:
Allah said, (Let there arise out of you a group of people) that calls to righteousness, enjoins all that is good and forbids evil in the manner Allah commanded, (And it is they who are the successful.)
Ad-Dahhak[3] said, "They are a special group of the Companions and a special group of those after them, that is those who perform Jihad and the scholars.''
The objective of this Ayah is that there should be a segment of this Muslim Ummah fulfilling this task, even though it is also an obligation on every member of this Ummah, each according to his ability
Tafsir Ibn Kathir Vol 2 Page 232 (Darussalam English Translation)
The foundation
In Islam enjoining good and forbidding evil is one of the duties of a Muslim. Allah said:
You [true believers in Islamic Monotheism, and real followers of Prophet Muhammad SAW and his Sunnah (legal ways, etc.)] are the best of peoples ever raised up for mankind; you enjoin Al-Ma’ruf (i.e. Islamic Monotheism and all that Islam has ordained) and forbid Al-Munkar (polytheism, disbelief and all that Islam has forbidden), and you believe in Allah. And had the people of the Scripture (Jews and Christians) believed, it would have been better for them; among them are some who have faith, but most of them are Al-Fasiqun (disobedient to Allah - and rebellious against Allah's Command).
Al Imran (3) 110[1]
In another verse,
Let there arise out of you a group of people inviting to all that is good (Islam), enjoining Al-Ma’ruf (i.e. Islamic Monotheism and all that Islam orders one to do) and forbidding Al-Munkar (polytheism and disbelief and all that Islam has forbidden). And it is they who are the successful.
Al Imrân (03) Verse 104.
In his Tafsir, Ibn Kathir[2] said:
Allah said, (Let there arise out of you a group of people) that calls to righteousness, enjoins all that is good and forbids evil in the manner Allah commanded, (And it is they who are the successful.)
Ad-Dahhak[3] said, "They are a special group of the Companions and a special group of those after them, that is those who perform Jihad and the scholars.''
The objective of this Ayah is that there should be a segment of this Muslim Ummah fulfilling this task, even though it is also an obligation on every member of this Ummah, each according to his ability
Tafsir Ibn Kathir Vol 2 Page 232 (Darussalam English Translation)
The Consequences
This duty is so important such that neglecting on acting upon it is equated with the collective punishment of Allah upon the people, whether they are good or bad if those who are good amongst them neglect to implement it. Imam Bukhari collected a hadeeth narrated By Zainab bint Jahsh:
The Prophet got up from his sleep with a flushed red face and said, "None has the right to be worshipped but Allah. Woe to the Arabs, from the Great evil that is nearly approaching them. Today a gap has been made in the wall of Gog and Magog like this." (Sufyan illustrated by this forming the number 90 or 100 with his fingers.) It was asked, "Shall we be destroyed though there are righteous people among us?" The Prophet said, "Yes, if evil increased."
Vol 9, Book 88. Book of Afflictions and the end of the world. Hadeeth number 181[4]
And its fulfillment is connected to our safety:
O you who believe! Take care of your ownselves, [do righteous deeds, fear Allah much (abstain from all kinds of sins and evil deeds which He has forbidden) and love Allah much (perform all kinds of good deeds which He has ordained)]. If you follow the right guidance and enjoin what is right (Islamic Monotheism and all that Islam orders one to do) and forbid what is wrong (polytheism, disbelief and all that Islam has forbidden) no hurt can come to you from those who are in error. The return of you all is to Allah, then He will inform you about (all) that which you used to do.
Al Maaidah (5): 105
…and Allah will grant us power in the land:
Those (Muslim rulers) who, if We give them power in the land, (they) order for Iqamat-as-Salat. [i.e. to perform the five compulsory congregational Salat (prayers) (the males in mosques)], to pay the Zakat and they enjoin Al-Ma'ruf (i.e. Islamic Monotheism and all that Islam orders one to do), and forbid Al-Munkar (i.e. disbelief, polytheism and all that Islam has forbidden) [i.e. they make the Qur'an as the law of their country in all the spheres of life]. And with Allah rests the end of (all) matters (of creatures).
Al Hajj (22): 41
The Methodology
The methodology of enjoining good and forbidding evil is enshrined in a hadeeth collected by Imam Muslim:
It is narrated on the authority of Tariq b. Shihab: It was Marwan who initiated (the practice) of delivering khutbah (address) before the prayer on the 'Id day. A man stood up and said: Prayer should precede khutbah. He (Marwan) remarked, This (practice) has been done away with. Upon this Abu Sa'id remarked: This man has performed (his duty) laid on him. I heard the Messenger of Allah as saying: He who amongst you sees something abominable should modify it with the help of his hand; and if he has not strength enough to do it, then he should do it with his tongue, and if he has not strength enough to do it, (even) then he should (abhor it) from his heart, and that is the least of faith.
Book 1 Faith. Hadeeth No. 79
In another narration:
It is narrated on the authority 'Abdullah b. Mas'ud that the Messenger of Allah (may peace and blessings be upon him) observed: Never a Prophet had been sent before me by Allah towards his nation who had not among his people (his) disciples and companions who followed his ways and obeyed his command. Then there came after them their successors who said whatever they did not practise, and practised whatever they were not commanded to do. He who strove against them with his hand was a believer: he who strove against them with his tongue was a believer, and he who strove against them with his heart was a believer and beyond that there is no faith even to the extent of a mustard seed.
Sahih Muslim. Book 1. Faith. Hadith 0081.
It is done according to position and authority
'Abdullah bin 'Umar had said, "I heard Allah's Apostle saying, 'All of you are guardians and responsible for your wards and the things under your care. The Imam (i.e. ruler) is the guardian of his subjects and is responsible for them and a man is the guardian of his family and is responsible for them. A woman is the guardian of her husband's house and is responsible for it. A servant is the guardian of his master's belongings and is responsible for them.' I thought that he also said, 'A man is the guardian of his father's property and is responsible for it. All of you are guardians and responsible for your wards and the things under your care."
Sahih Bukhari Vol 2, Book 13. Friday Prayer. Hadith 018
Implementing the Methodology with Wisdom
Enjoining good and forbidding evil is essentially inviting people to Allah. In this regard, Allah said in the Qur’an:
Invite (mankind, O Muhammad) to the Way of your Lord (i.e. Islam) with wisdom (i.e. with the Divine Inspiration and the Qur'an) and fair preaching, and argue with them in a way that is better. Truly, your Lord knows best who has gone astray from His Path, and He is the Best Aware of those who are guided.
Surah/Chapter 016 - An-Nahl. Verse 125.
Implementing with wisdom means we must make sure according to the best of our abilities that when we enjoin good or forbid evil, the end result would be beneficial. In other words a greater good should be achieved or a greater evil is prevented.
There are many circumstances when we want to do good yet the result is harm. One example is praying the Tahajjud prayer but neglecting to pray the Fajr prayer due to exhaustion. One does not do the voluntary acts of worship in lieu of the Waajib. Because of this one does not pray the Sunnah prayer once the Iqaamah has been announced.
Likewise there are also circumtances where we want to avert harm yet the result is greater harm. To illustrate this point, we will mention the hadeeth narrated by Anas bin Malik in Sahih Muslim:
A Bedouin came and passed urine in one corner of the mosque. The people shouted at him but the Prophet stopped them till he finished urinating. The Prophet ordered them to spill a bucket of water over that place and they did so.
Vol 1 Book 4 Ablutions Hadeeth no. 234
Had the Prophet sallallahu alaihi wasallam did not prevent the people from stopping the man from urinating, that man would have had splashed his urine all over the place, or in people’s clothings instead of confining it only to the place where he is urinating. Further, abruptly stopping the urination process could have other bad effects to a person’s health. Thus a greater harm was prevented by allowing some lesser harm to occur.
Ask Allah’s help
There is a Sunnah prayer called Istikhaara prayer. One is supposed to perform this prayer if he/she is going to decide on something.
Finally enjoining good and forbidding evil should be done for the sake of Allah alone. Further it should be done according to the way of the Prophet sallallahu alaihi wasallam.
We ask Allah that if we perform this obligation, we will be from those who are rewarded and be those whose scale of good deeds in the Judgment Day is heavy.
Narrated By 'Amr bin Al-'As: That he heard Allah's Apostle saying, "If a judge gives a verdict according to the best of his knowledge and his verdict is correct (i.e. agrees with Allah and His Apostle's verdict) he will receive a double reward, and if he gives a verdict according to the best of his knowledge and his verdict is wrong, (i.e. against that of Allah and His Apostle) even then he will get a reward."
Summary
Muslims are required to enjoin good and forbid evil. Its implementation and neglect are linked to our success and failure respectively. Its effectuation is done with wisdom and according to one’s authority. Finally it is Allah who grants success.
[1] All Qur’anic quotations are taken from islamsoft solutions. Downloadable free from http://www.islamtomorrow.com/
[2] A Great Scholar of Qur’an interpretation. http://www.tafsir.com/
[3] A Great Scholar amongst the early generations of Muslims.
[4] All Hadeeth quotations are taken from islamsoft solutions.