Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: The Prophet of Allah (peace and blessings be upon him) sent out an army, and its banner was turned back. Then he (peace and blessings be upon him) sent it (again), and it was turned back because of the misappropriation of a golden gazelle's head. Then this verse was revealed: "And it is not for any prophet to act unfaithfully" [Al Imran: 161].
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12630