It was narrated that Anas bin Malik said:
"The Messenger of Allah said: 'I have been tortured for the sake of Allah as no one else has, and I have suffered fear for the sake of Allah as no one else has. I have spent three days when Bilal and I had no food that any living being could eat but that which could be concealed in the armpit of Bilal.'"
English reference: Vol. 1, Book 1, Hadith 151
Arabic reference: Book 1, Hadith 156