Hadith - Bukhari's Book of Manners #271, Abu Dawud, Tirmidhi, Ahmad, and Ibn Hibban.
...Abu Darda' reported that the Prophet of Allah, upon him be peace, said, "Nothing is weightier on the Scale of Deeds than one's good manners."
Hadith - Bukhari's Book of Manners #286 and Ahmad
Abu Huraira, r.a., said, "I heard Abu al Qasim (the Prophet saaws), say, 'The best among you in Islam are those with the best manners, so long as they develop a sense of understanding.' "
Hadith - At-Tabaraanee collected it, and Albani authenticated it in Silsilatul-AHaadeethis-Saheehah (#432).
The Prophet (saaws) said: "The most beloved of Allah's servants to Allah are those with the best manners."
Hadith - Sahih Bukhari, Muslim, and Tirmidhi
... 'Abd Allah ibn 'Amr said, "The Prophet of Allah, upon him be peace, was never obscene or coarse. Rather, he used to tell us that the best among us were those with the best manners."
Hadith - Sahih Bukhari, Muslim and Ahmad
... Anas said, "I served the Prophet of Allah, upon him be peace, for ten years. During that time, he never once said to me as much as 'Oof' if I did something wrong. He never asked me, if I had failed to do something, 'Why did you not do it?,' and he never said to me, if I had done something wrong, 'Why did you do it?' "
Hadith - Bukhari's Book of Manners # 285, Hakim, and Abu Dawud
... Abu Huraira, r.a., said that the Prophet of Allah, saaws, said, "If one has good manners, one may attain the same level of merit as those who spend their nights in prayer."
Hadith - Bukhari's Book of Manners # 290, Tirmidhi, Ibn Majah, and Ahmad
... Abu Hurairah reported that the Prophet of Allah (saaws) said, "And what is most likely to send people to Paradise? Being conscious of Allah and good manners."
Hadith - Bukhari's Book of Manners # 296, Muslim, Tirmidhi, Darimi, Abu 'Awanah, Hakim, and Ibn Hibban.
... Nawas ibn Sam'an reported that the Prophet of Allah, saaws, was asked about doing good and evil. He replied, "Doing good is having good manners. Doing evil is what troubles you inside and what you would not like others to know about."
Hadith - Bukhari's Book of Manners #360, Abu Dawud, Tirmidhi, and Hakim
The Prophet of Allah, saaws, said, "He who does not show mercy to our young or show esteem for our elders is not one of us."
The sin of finding faults in others
Hadith - Bukhari's Book of Manners #313, Ahmad, Ibn Hibban, and Hakim
... 'Abd Allah reported that the Prophet of Allah, upon him be peace, said, "A believer is not a fault-finder and is not abusive, obscene, or course."
Hadith - Bukhari's Book of Manners #329
... Ibn 'Abbas said, "If you wish to mention the faults of your friend, mention your own faults first."
Hadith - Bukhari's Book of Manners #330
... Ibn 'Abbas said on the following verse of the Qur'an, "Nor defame one another" (49:11), "Do not spend your time finding fault with one another."
Hadith - Bukhari's Book of Manners #545
Jubayr ibn Nufayr reported that Mu'adh ibn Jabal said, "If you love someone, do not quarrel with him and do not annoy him. Do not ask others about him, for the one you ask might be his enemy and thus tell you things about him that are not true and thus break you apart."
Hadith - Bukhari's Book of Manners #889 and Ibn Hibban
'Amr ibn al 'As said, "...I am amazed at one who spots an impurity in the eye of another but is unable to detect it in his/her own eye, or who attempts to remove a grudge from another's heart while making no attempt to remove grduges from his/her own heart. I have never blamed anyone for the confidences of mine that they have betrayed. How could I, when already they have given me reason for pause?"
Hadith - Bukhari's Book of Manners #1295
Bilal ibn Sa'd al Ash'ari reported that Mu'awiyah wrote to Abu Darda' "Write to the wrongdoers of Damascus." So he asked, "What do I have to do with the wrongdoers of Damascus? How will I know them?" Abu Darda's son, Bilal said, "I will write to them," which he did. Then Abu Darda' said [to Bilal], "How did you know to whom to write? You could not have known they were wrongdoers unless you were one of them. Begin with yourself!" So he did not address the letter in anyone's name.*
*i.e. he didn't single out a specific person as a wrongdoer, but spoke about wrongdoings in general, to come as a reminder (of Quran and Sunnah) to the people.
Group Conversations
Hadith - Sahih Bukhari, Muslim, Abu Dawud, and Ibn Majah
'Abd Allah ibn Mas'ud reported that the Prophet of Allah, upon him be peace, said, "If they are three, two of them should not carry on a conversation from which the third is excluded, for surely that will be distressing to him."
Hadith - Bukhari's Book of Manners, Abu Dawud. Ibn Hibban classified the hadith as authentic.
Ibn 'Umar reported the same from the Prophet, upon him be peace. Except that in the end, he added, "We asked, 'If they are four?' He, upon him be peace, said, 'Then there is no harm.' "
Beware of Suspicion
Hadith - Sahih Bukhari, Muslim, Abu Dawud, Tirmidhi, Ibn Majah, Ahmad, and Ibn Hibban
Abu Huraira, r.a., reported that the Prophet of Allah, upon him be peace, said, "Be careful of suspicion, for it is the most mistaken of all speech. Do not spy on others, compete* among yourselves, envy one another, or despise one another. Rather, be servants of Allah and brothers!"
*There is nothing wrong with healthy competition, particularly in doing good deeds. This hadith refers to competion that destroys team play and equality, etc.)
Hadith - Bukhari's Book of Manners #1294
'Abd Allah said, "Sometimes a victim of robbery will become so suspicious [of everyone around him] that he will become worse than the thief."*
*In other words, his suspicions will lead him to doubt everyone until he has destroyed every one of his relationships.
It is permissible to call over a person and inform them of the facts, so that they will not be suspicious, as we see in the following hadith (narration).
Hadith - Bukhari's Book of Manners #1293, Muslim and Abu Dawud
Anas reported that a man passed by while the Prophet of Allah, upon him be peace, was with one of his wives. The Prophet called the man and said, 'O So and so. This is my wife, so and so." The man replied, What I might have thought about another, I would never think about you." The Prophet, upon him be peace, said, "Shaytan [satan] will circulate through a person just like blood circulates [through one's veins]."
Give Gifts
Hadith - Bukhari's Book of Manners #594, also related by Abu Ya'la and by Nasa'i in al Kuna.
Abu Huraira, r.a., reported that the Prophet of Allah, upon him be peace, said, "Give gifts to one another, and you will love one another."
Hadith - Sahih Bukhari, Muslim, Nasa'i and Tirmidhi
Ibn Abi Mas'ud al Badri reported that the Prophet of Allah, upon him be peace, said, "Anyone who spends money on his family and seeks blessings for doing so will find it counted as sadaqah (charity) on his behalf."
Have a sense of shame/shyness
(not being shy from doing good, but shyness from doing wrong)
Hadith - Sahih Bukhari, Abu Dawud, Ibn Majah, Ibn Hibban, and Ahmad
Abu Mus'ud reported that the Prophet of Allah, saaws, said, "Among the well-known wisdom of the prophets is the saying, 'If you have no shame, then do as you please.' "
Hadith - Sahih Bukhari, Muslim, Nasa'i, Abu Dawud, Ibn Majah, and Tabarani
Abu Huraira, r.a., reported that the Prophet, saaws, said, "... Having a sense of shame is one branch of faith."
Hadith - Sahih Bukhari, Muslim and Ibn Majah
'Abd Allah ibn Abi 'Atabah said that he heard Abu Sa'id say, "The Prophet of Allah, upon him be peace, was shyer than a virgin in her shift. Whenever he disliked something, we could see it on his face."
The sin of Pride
Hadith - Bukhari's Book of Manners #550
Abu Huraira, r.a., reported that the Prophet of Allah, upon him be peace, said, "Whoever eats with his servant, or rides a donkey in the marketplace, or who ties up his goat and milks it will no be guilty of the sin of pride.
Hadith - Bukhari's Book of Manners #556, Abu Dawud and Tirmidhi
Abu Huraira, r.a., reported that a handsome man went to the Prophet of Allah, upon him be peace, and said, "I love beauty, and I have been given what you see, even to the extent of my hating to be bested. Is that pride?" The Prophet replied, "No. Rather, pride is to disdain the truth and to treat others with contempt."