Translation:

143. Thus have We made of you an Ummah justly balanced that ye might be witnesses over the nations and the Apostle a witness over yourselves; and We appointed the Qiblah to which thou wast used only to test those who followed the Apostle 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.

Notes (Tafseer)

142. Thus: By giving you a Qibla of your own, most ancient in history, and most modern as a symbol of your organisation as a new nation (Ummat).

143. Justly balanced: The essence of Islam is to avoid all extravagances on either side. It is a sober, practical religion. But the Arabic word (wasat) also implies a touch of the literal meaning of Intermediacy. Geographically Arabia is in an intermediate position in the Old World, as was proved in history by the rapid expansion of Islam, north, south, west and east.

144. Witnesses: When two persons dispute, they advance extravagant claims. A just witness comes between them, and brings the light of reason to bear on them, pruning all their selfish extravagances. So the mission of Islam is to curb, for instance, the extreme formalism of the Mosaic law and the extreme "other-worldiness" professed by Christianity. The witness must be unselfish, equipped with first-hand knowledge, and ready to intervene in the cause of justice. Such is the position claimed by Islam among rival systems. Similarly, within Islam itself, the position of witness to whom disputants can appeal is held by Muhammad Mustafa.

145. The Qibla of Jerusalem might itself have seemed strange to the Arabs, and the change from it to the Ka'ba might have seemed strange after they had become used to the other. In reality one direction or another, or east or west, in itself did no matter, as God is in all places, and is independent of Time and Place. What mattered was the sense of discipline, on which Islam lays so much stress: which of us is willing to follow the directions of the chosen Apostle of God? Mere quibbles about non-essential matters are tested by this.

146. What became of prayer with the Jerusalem Qibla? It was equally efficacious before the new Qibla was ordained. God regards our faith: every act of true and genuine faith is efficacious with Him, even if formalists pick holes in such acts.