Bismillahir Rahmaanir Raheem
Rasulullah
Sallallaahu 'alayhi wasallam
said:
"The best Dua is the Dua on the Day of Arafah, and
the best of what I and the Ambiyaa before me have said, is: 'There is no god
except Allah; He is Alone and has no partner; to Him belongs the Dominion and
to Him belongs all Praise, and He has Power over everything.'"
~ Tirmidhi