The messenger of Allah (May the Peace and Blessings of Allah be upon him said): If a mishap should happen to befall you then do not say, “If only I had acted…such and such would have happened.” Rather, say:

“Allah has decreed and what He wills, He does.”

…for verily (the word) 'IF' lets in the work of the devil.

qaddar-allaahu wa maa shaa’a fa‛al