In times of distress, in great difficulty, when it appeared there was no hope left, what dua did the Prophet (pbuh) say?

The Prophet Ibrahim (as) said this dua also!  When the Prophet Ibrahijm was about to be thrown into the fire of Nimrud, he was just 14 or 15 years old, and he was the only Muslim in the world at that time. The mighty kings surrounded him and threatened him for 3 days and made a fire to throw him into. 

The dua they made was “HasbunAllahu ni’amel wakeel” 

When you say this dua you affirm the power of Allah. You are affirming that Allah is the only one who can help me and  I put all my trust in Him.