First let's see what did the Quran and the Prophet say about Akhlaaq (manners):
The Prophet Mohammad (peace be upon him), in Muwatta Imam Malik said: "Verily, I was sent for no other reason,except to perfect the noble traits of character'' - in other words; one of the Prophet's goals, in fact, the primary mission was the perfection of how people behave - their manners.
A Muslim can't be a true Muslim if he does his Ibadaat (worshiping, i.e prayers, fasts, zakat..etc)very well but neglects an important side of his worship i.e Akhlaaq. In other words, he who prays his daily prayers in mosques well, but when it comes to dealing with people in his daily life he is the worst person, cannot be considered a true Muslim. This is true of people who backbite, spreading hate and evil among people, treat those who are under his care (family, employees…etc) cruelly and lie. Yet people who are like this are still proud of themselves and think that they are guaranteed a place in Jannah because of their prayers?
The connection between Iman and manners is very strong as the Prophet peace be upon him said that faith consists of seventy branches, the least of which is the removal of a tree branch blocking the road, and in another narration, sixty branches, and Hayaa' (which is an Arabic term, which is hard to translate and covers manners,modesty, guarding of chastity, etc) is a part of faith. So again, manners and behavior are linked directly to Iman.
The Prophet sal Allaahu alayhi wa sallam said: "The best Mu'mins(believers) are those who are best in their akhlaaq, those whose shoulders' are trodden over."
The Prophet peace be upon him said: "Those of you who will be closest to me on the Day of Judgment will be those who have the best akhlaaq."
Is there any better blessing than being close to the Prophet in the day of judgment?
Now lets see how and where the good manners are demanded
In the area of family, the Prophet (peace be upon him) said: The best of you is the best of you to his family, and I am the best to his family.
In the area of neighbors, the Prophet (peace be upon him) said: The angel Gabriel kept advising me about neighbors until I thought he would make him entitled to some part of the inheritance.
In speech, the Prophet (peace be upon him) said: Nothing is weightier on the scales of the day of judgment than his good behavior.Allah treats a person who is given to loose and vulgar talk with displeasure.
With regards to backbiting,the Allah said: And do not backbite, would one of you like to eat the flesh of his dead brother; you would surely hate it (so you should likewise hate backbiting) [Al Quran 49:12].
With regards to parents, Allah said: say not even a word to them in contempt and don't repel them [Al Quran 17:23].
In controlling one's temper, the Prophet (peace be upon him) says: The strong man is not the good wrestler, but the strong man is he who controls himself when he is angry.
With regards to being for giving and kind, the Prophet (peace be upon him), said to one of the Sahabah: ``You have two qualities which Allah (Subhanahu Wa Ta'alaa) likes and loves: one is mildness and the other is toleration''.
Ahklaaq in giving Dawah:
You might believe this or not! But good manners are the best form of Dawah. If we ask ourselves, what if a person was walking around calling people to Islam and to worship the one true God yet he have no manners at all, will anyone follow him? Or even listen tohim? The answer must be No, for sure.
No one will be willing to follow the same way of life that such a person (above) follows. Even if he was so eloquent in his speech and no matter how nicely he described Islam as the best religion on the face of earth, his actions, speech,and beliefs are opposing hence no one will listen to him.People tend to believe the actions more than the speech and that is the nature of human as actions speak louder than words
We need to remind ourselves that Islam was spread -during its early stages- in many countries like India and the far east of Asia through the Arab Muslim merchants who were showing the best of manners -especially in trade- to people of those countries. Their honesty and actions were so admired by people of those countries that they embraced Islam.
You can't walk around preaching people to embrace the religion of honesty when you are not honest! You can't advise people about morality in Islam when you don’t follow any morals! No one will believe what you are saying because simply you are not making any sense to them!
Another example of this is the story of the Jew who was a neighbor of the Prophet (peace be upon him) who used to dump rubbish on his doorstep. One day, the Prophet found no rubbish. The next day he found no rubbish, so he asked about the Jew, only to find that he was sick. He then visited the sick Jew and tried to make him feel better. As a result, the Jew became Muslim.
So how do we improve our manners?
Imitation One way to learn how to do something is to pick a master at that particular thing and learn from him. And indeed in Prophet Muhammad (peace be upon him) we find that excellent example. In the Qur'an we find it says (In suratul Ahzaab, 33: 21). Indeed you have in the messenger of Allah an excellent example for anyone who him who looks to Allah and the Final Day and remembers Allah a lot. And in another verse in (Suratul Qalam 68: And you (i.e the prophet) are indeed possessedof awesome manners. Ai'sha (may Allah be pleased with her) when asked about the behavior of the Prophet (peace be upon him) said that ``His manners were the Qur'an''.So we should study the manners of the Prophet and try our best to imitate them. [The Great Importance of Good Manners by Muslims, A khutbah (sermon) by M. Waleed Kadous]