The Prophet (PBUH) loved Imam Hossein (PBUH) very much. His companion Salman Farsi describes, "I saw that the Prophet (PBUH) had picked up Imam Hossein (PBUH) upon his knee and was kissing him saying, "Oh son, you are the Imam, son of Imams and father of nine Imams, who would be from your generation and the last of them is Mahdi." One can estimate and guess the amount of love the Prophet had with Imam Hossein (PBUH) from this sentence of his "Hosein is from me and I am from Hosein. The one who is the friend of Hasan and Hossein is my friend and the one who is their enemy, is my enemy."
Zadhan reported on the authority of Salman:
"I heard the Apostle of God, may God bless him and his family, say concerning Hasan and Hosein, peace be on them: O God, I love both of them. Therefore love them and love whoever loves them. Then he said: Whoever loves Hasan and Hosein is one whom I love. Whomever I love, God loves, and whomever God loves, He will cause to enter Heaven. Whoever hates them, I hate and God hates. Whomever God hates, He will cause to enter the Fire. Then he said: These two sons of mine are my two plants of sweet basil (to sweeten) the world.
Reference:
Kitab al Irshad By Sheikh al Mufid
source : tebyan