Al-Baqarah - 2:143

وَكَذَلِكَ جَعَلْنَاكُمْ أُمَّةً وَسَطًا لِّتَكُونُواْ شُهَدَاء عَلَى النَّاسِ وَيَكُونَ الرَّسُولُ عَلَيْكُمْ شَهِيدًا وَمَا جَعَلْنَا الْقِبْلَةَ الَّتِي كُنتَ عَلَيْهَا إِلاَّ لِنَعْلَمَ مَن يَتَّبِعُ الرَّسُولَ مِمَّن يَنقَلِبُ عَلَى عَقِبَيْهِ وَإِن كَانَتْ لَكَبِيرَةً إِلاَّ عَلَى الَّذِينَ هَدَى اللّهُ وَمَا كَانَ اللّهُ لِيُضِيعَ إِيمَانَكُمْ إِنَّ اللّهَ بِالنَّاسِ لَرَؤُوفٌ رَّحِيمٌ
[2:143]
And thus We have made you a medium (just) nation that you may be the bearers of witness to the people and (that) the Messenger may be a bearer of witness to you; and We did not make that which you would have to be the qiblah but that We might distinguish him who follows the Messenger from him who turns back upon his heels, and this was surely hard except for those whom Allah has guided aright; and Allah was not going to make your faith to be fruitless; most surely Allah is Affectionate, Merciful to the people.
Thus, have We made of you an Ummat justly balanced, that ye might be witnesses over the nations, and the Messenger a witness over yourselves; and We appointed the Qibla to which thou wast used, only to test those who followed the Messenger from those who would turn on their heels (From the Faith). Indeed it was (A change) momentous, except to those guided by Allah. And never would Allah Make your faith of no effect. For Allah is to all people Most surely full of kindness, Most Merciful.
Thus We have appointed you a middle nation, that ye may be witnesses against mankind, and that the messenger may be a witness against you. And We appointed the qiblah which ye formerly observed only that We might know him who followeth the messenger, from him who turneth on his heels. In truth it was a hard (test) save for those whom Allah guided. But it was not Allah's purpose that your faith should be in vain, for Allah is Full of Pity, Merciful toward mankind.