The Muslims are one Ummah --- all Muslims are like a part of a body. The true and sincere Muslims are merely one of the categories of the children of Aadam alayhis salaam, and that the Muslims are like a single body and a single structure; each part supporting the other and each part feeling the pain that the other parts are suffering as occurs in an authentic hadeeth (narration) from Rasoolullah sallallahu alayhi wasallam, that he said: "The Believer to the Believer is like a solid building, one part supports the other." And he interlaced his fingers to demonstrate this. [Related by Bukhaaree (No.481) and Muslim (No.2585) from Abu Hurayrah radhiyallaahu anhu]
Rasoolullah sallallahu alayhi wasallam also said: "The example of the Believer in their mutual love and mercy is like the example of a body, if one part of the body feels pain, then all the body suffers in sleeplessness and fever. [Related by Bukhaaree (No.6011) and Muslim (No.2586) from an-Nu'maan ibne Basheer radhiyallaahu anhu]
Racialism, nationalism and genealogical differences have broken their unity and have planted enmity. This has hatred of each other in their hearts and a fragmentation and splitting between tribes and nations.
Rasoolullah sallallahu alayhi wasallam said: "Whosoever leaves off obedience and separates from the Jamaa'ah and dies, he dies a death of jaahiliyyah. Whoever fights under the banner of the blind, becoming angry for 'asabiyyah (partisanship and party spirit), or calling to 'asabiyyah, or assisting 'asabiyyah, then dies, he dies a death of jaahiliyyah."
[Related by Muslim (6/21), from Abu Hurayrah radhiyallaahu anhu]
At-Tirmidhee relates from Rasoolullah sallallahu alayhi wasallam that he said: "Let people stop boasting about their forefathers who have died, who are merely fuel for the Fire of Hell; or they will certainly be more insignificant with Allah than the beetle which roles dung with its nose. Allah has removed from you the party spirit of the days of jaahiliyyah and the boasting about one's forefathers. Indeed a person is either a pious Believer or a wretched sinner. All of mankind is the children of Aadam, and Aadam was created from clay." [Hasan: Related by Abu Daawood (No.5116) and at-Tirmidhee (No.4233) from Abu Hurayrah radhiyallaahu anhu]
Rasoolullah sallallahu alayhi wasallam also said: "Indeed there is no excellence for an Arab over a non-Arab, nor a non-Arab over an Arab, nor a white person over a black one, nor a black person over a white one, except through taqwaa (piety and obedience to Allah)" [Saheeh: Related by Ahmad (5/411)]
And this accords with Allah the Most High's saying:
"O mankind! We have created you from male and female and have made you into nations and tribes, that you may know one another. Indeed the most noblest of you with Allah is the one who has the most taqwaa." [Soorah al-Hujuraat 49:13].
O people! Does your nationalism call you to these noble manners of mercy and kindness to the Muslims the Arabs and the non Arabs and of having mutual sympathy and concern for them, and feeling pain at their pain? No by Allah! Rather it calls you to having allegiance with those who have evil character and it calls you to cultivating enmity and hatred for those who deny this false creed of nationalism. So beware, O Muslim who desires safety and salvation, and consider the reality of the affair with a fair consideration, without being prejudiced with party spirit and desires. Only then you will see the reality as it truly is.