One day Abu Jahl came to the prophet and said, "You have the most ugly face in Bani Hashim." Abu Jahl as we all know was a chief from the Quraysh tribe who showed the most hatred towards Islam.
The Prophet said, "You speak the truth."
Soon afterwards, Sayyiduna 'Umar (RA) came in and remarked, "O Prophet of Allah, your face shines like the brilliant sun." The Prophet replied, "You speak the truth."
A companion of the Prophet who was sitting nearby asked, "How can it be possible that both the opposite remarks are true?"
The Prophet replied, "I am like a clean shining mirror. Everyone sees his own face in me"