Well before being a part of this discussion, I used to believe as per my own observation, that num 3 is significant in Islam.

Prophet Mohammad SAW used to repeat any significant phrase three times when he was to emphasize something.
During ablation (wuzu), as per sunah he wash three times each body part that needs to be washed.
We repeat ‘Subhaana Rabbiyal-Azeem’ (Pure is my Lord, the Great) and ‘Subhaana Rabbiyal Aalaa’ (Pure is my Lord, the Supreme) in ruku and sajda respectively.
Ramzan has three ashras.
One has to fast for three days if (s)he breaks a promise.
A Muslim is asked three times in nakah and as a witness.

And the list goes on....

__________________
"Life is either a daring adventure or nothing."
Helen Keller