The Prophet, (Peace and blessings be upon him) said: "By Allah, he is not a believer! By Allah, he is not a believer! By Allah, he is not a believer.''
It was asked, "Who is that, O Messenger of Allah?''
He said, "One whose neighbour does not feel safe from his evil"
2) Recommendation to treat neighbour well
The Messenger of Allah, (Peace and blessings be upon him), said: "Jibril kept recommending me to treat my neighbour well until I thought that he would tell me to make him one of my heirs" (Bukhari:6014)
3) Caring for your neighbours
Abu Dharr, May Allah be pleased with him, reported: The Messenger of Allah, (Peace and blessings be upon him), commanded me thus, "O Abu Dharr! Whenever you prepare a broth, put plenty of water in it, and give some of it to your neighbours".( Sahih Muslim)
4) Co-operation with your neighbors
Abu Hurayrah, may Allah be pleased with him, reported that the messenger of Allah, (Peace and blessings be upon him), said: "No-one should prevent his neighbour from fixing a wooden peg in his wall." Abu Huraira said (to his companions), "Why do I find you averse to it? By Allah, I certainly will narrate it to you."
5) Do not eat your full while your neighbor is hungry
The Messenger of Allah say:" He is not a believer who eats his fill whilst his neighbor beside him goes hungry" (Bukhari)
6) Never scorn your neighbor's gift
Sahih Abu Hurayrah reported that the Prophet, (Peace and blessings be upon him), used to say: "O Muslim women! No one should scorn the gift of a neighbor, even if it is (only) a sheep's foot"
7) Harming a neighbor may lead to hell-fire
Abu Hurayra, may Allah be pleased with him reported: A man asked, "O Messenger of Allah! There is a woman who prays, gives charity and fasts a great deal, but she harms her neighbors with her speech (by insulting them)"
He said: "She will go to hell"
The man said: "O messenger of Allah! There is (another) woman who is well-known for how little she fasts and prays, but she gives charity from the dried yoghurt she makes and she does not harm her neighbors"
He said: "She will go to paradise"
(Ahmad, vol. 4, p. 166, Ibn Hibban, hadith no. 2054)
8) Tolerance when treating neighbors
Mutarrif said: "I heard that you (he means Abu Dharr, may Allah be pleased with him) have said that the Prophet, (Peace and blessings be upon him), said: "Allah loves three and hates three.'"
Abu Dharr said, "I do not think that I would tell lies about the Messenger of Allah."
Mutarrif said, "Then who are the three whom Allah loves?"
Abu Dharr (quoting the Prophet, (Peace and blessings be upon him)) said: "A man who fights for the sake of Allah, with perseverance and hoping for reward from Him, and fights until he is killed, and you find this in the Book of Allah.' Then he recited: "Truly Allah loves those who fight in His cause in battle array, as if they were a solid cemented structure." [al-Saff 61:4] Mutarrif asked, "Then who?"
He said, "A man who has a bad neighbor who annoys and disturbs him, but he bears it with patience and forbearance until Allah ends the matter either during his lifetime or upon the death of either of them."
( Reported with a sahih isnad by Ahmad and al-Tabarani. See Majma' al-Zawa'id, 8/171.)