Qur'an, Al-Baqara, Surah 2:144
We observe you as you turn your face toward the heaven seeking guidance. We enjoin you now to turn in prayer toward the Qibla. Therefore turn your face toward the inviolable House of Worship. And all of you, wherever you may be, turn your faces toward it. Behold those who have received the Scriptures know that this revelation is the Truth. Allah is cognizant of what they do.