Narrated Isma’il bin Abi Khalid:
I heard Abii Juhaifa saying, “I saw the Prophet, and Al-Hasan bin ‘Ali resembled him.” I said to Abu- Juhaifa, “Describe him for me.” He said, “He was white and his beard was black with some white hair. He promised to give us 13 young she-camels, but he expired before we could get them.”
Sahih Bukhari, Volume 4, Book56, Number 744