The Office of the Judge (Kitab Al-Aqdiyah)
Dawud :: Book 24 : Hadith 3620
Narrated Awf ibn Malik:
The Holy Prophet (peace_be_upon_him) gave a decision between two men, and the one against whom the decision was given turned away and said: For me Allah sufficeth, and He is the best dispenser of affairs. The Holy Prophet (peace_be_upon_him) said: Allah, Most High, blames for falling short, but apply intelligence, and when the matter gets the better of you, say; For me Allah sufficeth, and He is the best disposer of affairs.