Ibn Mas`ud (May Allah be pleased with him) reported: I visited the Prophet (PBUH) while he was suffering. I said: "(O Messenger of Allah!) You suffer too much." He said, "Yes, I suffer as much as two men of you."[Al-Bukhari and Muslim].
This Hadith also throws light on the fact that the Prophet (PBUH) was merely a human being. Besides, it tells us that one is at liberty to speak of one's suffering.