And God's is the east and the west: and wherever you turn, there is God's countenance. Behold, God is infinite, all-knowing.
Al-Baqara (The Cow) Verse 115
Whenever the Prophet asked permission to enter, he knocked the door thrice with greeting and whenever he spoke a sentence (said a thing) he used to repeat it thrice.
Sahih Bukhari: Volume 1, Book 3, Number 94