Praise be to Allah.
The believer should be good-natured, treat others kindly, be gentle, be cheerful, and feel at ease with people and they with him, so that they may see in his good qualities the attributes of the people of Islam, and they may see him embodying the teachings of Islam. So he should be neither harsh and rough nor soft and foolish; he should not seek to please people by doing that which incurs the wrath of Allah, and he should not fear the blame of anyone for the sake of Allah. Righteousness should not prevent him from smiling or having a sense of humour and the ability to joke, and it should not prompt him to be isolated from people and refrain from mixing with them; rather he mixes with people, greets them, smiles at them, shakes hands with them, jokes with them and treats them kindly, and he makes that a means of calling them to Allah, advising them and guiding them. So he is close to people and is not remote from them; he mixes with them and shares their joys and sorrows. So you will find him to be a true brother who helps his Muslim brother, a sincere companion and close friend who rejoices with him at times of joy and mourns with him at times of sorrow; he consoles him if something bad befalls him. You will not find anyone who is more caring towards people than a Muslim who is following the noble teachings of Islam.
The Sunnah encourages this good attitude and good manners and behaviour. We will mention a few examples below.
At-Tabaraani narrated in al-Mu‘jam al-Awsat (4422) that Abu Sa‘eed al-Khudri said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “The most perfect of the believers in faith are those who are best in manners and attitude, who are humble, who feel at ease with people and people feel at ease with them. He is not one of us who does not feel at ease with people and they do not feel at ease with him.” Classed as hasan by al-Albaani in as-Saheehah (751).
What is meant by “humble” is those who are gentle and do not offend or upset the one who befriends them.
Al-Bazzaar (9319) narrated from Abu Hurayrah (may Allah be pleased with him) that the Prophet (blessings and peace of Allah be upon him) said: “Verily you cannot afford to make people happy with your wealth, but you can make them happy with you by means of a cheerful face and good attitude.” Classed as hasan by al-Albaani in Saheeh at-Targheeb (2661).
Al-Bukhaari (6927) and Muslim (2593) narrated from ‘Aa’ishah (may Allah be pleased with her) that the Messenger of Allah (blessings and peace of Allah be upon him) said: “Verily Allah is Kind and loves kindness, and He rewards for kindness in a way that He does not reward for harshness or for anything else.”
At-Tirmidhi (2488) narrated that ‘Abdullah ibn Mas‘ood said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Shall I not tell you of one who will be forbidden to the Fire, or for whom the Fire will become forbidden? Everyone who is close to people, gentle and easy-going.” Classed as saheeh by al-Albaani in Saheeh at-Tirmidhi.
Muslim (2626) narrated that Abu Dharr said: The Prophet (blessings and peace of Allah be upon him) said to me: “Do not regard any act of kindness as insignificant, even meeting your brother with a cheerful countenance.”
At-Tirmidhi (1956) narrated that Abu Dharr said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Your smiling at your brother is an act of charity.” Classed as saheeh by al-Albaani in Saheeh at-Tirmidhi.
At-Tirmidhi (1984) narrated that ‘Ali said: The Prophet (blessings and peace of Allah be upon him) said: “Verily in Paradise there are chambers, the outside of which may be seen from the inside, and the inside of which may be seen from the outside.” A Bedouin stood up and said: Who are they for, O Messenger of Allah? He said: “For those who speak kind words, give food, fast regularly, and pray at night when people are asleep.” Classed as hasan by al-Albaani in Saheeh at-Tirmidhi.
Al-Bukhaari (12) and Muslim (29) narrated from ‘Abdullah ibn ‘Amr (may Allah have mercy on him) that a man asked the Prophet (blessings and peace of Allah be upon him): What part of Islam is best? He said: “To feed others, and to greet with salaam those whom you know and those whom you do not know.”
Al-Bukhaari (6035) and Muslim (2321) narrated from ‘Abdullah ibn ‘Amr that the Messenger of Allah (blessings and peace of Allah be upon him) said: “Verily the best of you are those who are best in attitude.”
An-Nawawi (may Allah have mercy on him) said:
This offers encouragement to develop a good attitude, and it highlights the virtue of the one who does so. This is the attribute of the Prophets and close friends of Allah, may He be exalted. Al-Hasan al-Basri said: What is meant by good attitude is doing favours and refraining from harming others, and being cheerful.
Al-Qaadi ‘Iyaad said: It means mixing with people in a kind and cheerful manner, being friendly towards them and caring for them, putting up with them, being forbearing towards them, showing patience towards them at times of difficulty, not being arrogant towards them, avoiding being harsh and angry, and not rebuking or blaming them. End quote.
Whatever you do of smiling, feeling confident, being kind, having a sense of humour and mixing with people, within the limits and framework prescribed by Islam, without going to either extreme, whilst bearing in mind that the intention behind that is to call them to Allah, advise them, enjoin them to do what is right and forbid them to do what is wrong, is a wise thing to do and the best way of dealing with them; it is a step in the right direction with regard to da‘wah.
Whoever acquires the characteristics of the people of Islam, and treats people kindly, mixes with them and tries to get close to them, doing all of that for the sake of Allah and so that he can call them to Allah and advise them, will be rewarded on two counts, for acquiring good characteristics and for seeking to draw close to people in order to call them to Allah, without any ulterior motive or desire to seek worldly gain.
And Allah knows best.
Source: Islam Q&A