The Noble Qur'an tells us that all of mankind is descended from one couple, Adam and Eve. Thus we are all brothers and sisters, and our differences in languages and colors are but a mercy that we might know one another. Language and race should never be a reason for discriminating against people.
A Muslim should maintain good relations with his relatives, but he should not unjustly favor them over others. Further, a Muslim must be good to his neighbors, no matter their religion. But the Prophet Muhammad (peace and blessings be upon him) taught us that a "neighbor" is not just the one next door but includes all those up to forty houses in all directions - effectively a whole neighborhood.
An Ansar (emigrant) came to the Prophet Muhammad (peace and blessings be upon him) and said that he has recently purchased a house in a particular area and that his nearest person was such that he had no hope of any goodness from him and that he felt unsafe from his mischief. The Prophet Muhammad (peace and blessings be upon him) told Imam Ali (as), Salman Al-Farsi, Abu Zar Ghaffari and Miqdad ibn Aswad to go to the Mosque and announce: "He is not a believer whose neighbour is unsafe from his mischief." They announced it thrice and then to the Prophet Muhammad (peace and blessings be upon him) pointed towards forty doors to his right and forty to the left indicating that forty houses in every direction constitute ones neighbourhood. One is obliged to observe their rights.
This concern for our neighbors can take many forms. It means to ensure that our neighbors have the basic necessities, for a Muslim should not eat if his or her neighbor is going hungry. It means that Muslims should wish for their neighbors what they wish for themselves. It means sharing their happiness and sorrow. Further, it means to not spy on them and respect their privacy, to not gossip about them, to not harm them in any way, and to keep common use areas - such as apartment building entrances, streets and sidewalks - clean.
The Prophet Muhammad (peace and blessings be upon him) was told of a woman who prayed during night and fasted a lot during day and gave alms generously, but whose neighbors complained of her abusive tongue. He said that she would be in Hellfire. When the Prophet Muhammad (peace and blessings be upon him) was told of another woman who did not do all those extra acts of worship other than just compulsory (Wajib) but whose neighbors were happy with her, he said that she would be in Paradise. Thus we see the importance of being good to our neighbors, both in actions and words.