Was the failure that occurred part of the unchangeable divine decree, thereby comforting oneself, or was it a result of negligence?

What happened was by divine decree (qadar (definition)) and does not contradict shortcomings, for everything is by divine decree, even incapacity and cleverness. It is advised not to grieve over the past, but to strive in what is to come, to seek Allah's help, to be keen on what is beneficial, and not to be helpless. When afflicted with something, say: "Qaddar Allahu wa ma sha'a fa'al (Allah has decreed and what He willed, He did)," for indeed, "if only" opens the door to Satan's work.