question #2 Sahih al-Bukhari 3544, Book 61, Hadith 53 : What is the significance of the Prophet’s promise mentioned in the narration?

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.”