Qur'an, Al-Baqara, Surah 2:177
Piety does not consist in whether you face east or west during worship. True piety consists in this: believing in God and in his final judgement; believing in his angels, in the Book, and in the prophets; giving your wealth, for the sake of God, to your relatives, to orphans, to the needy, to wayfarers and to strangers; ransoming slaves; attending prayers and paying the poor-rate; being true to your promises; and being steadfast in times of distress, adversity and war. Those who show true piety, are genuine in their faith; they honour God.