Satan threatens you with the prospect of poverty and bids you to be niggardly, whereas God promises you His forgiveness and bounty; and God is infinite, all-knowing,
Al-Baqara (The Cow) Verse 268
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