Rasulullah (saw) said, be frequent in saying, There is no might or power except by Allah, (la hawla wa la quwwata illa billah). For verily, it is a treasure from the treasures of Paradise.
One of the many narrations about this dua, this one from Tirmidhi narrated by Abu Hurairah. It is a treasure from the treasures of Jannah. In Arabic and English.