General Behavior (Kitab Al-Adab)
Dawud :: Book 41 : Hadith 5212
Narrated A man:
Ghalib said: When we were sitting at al-Hasan's door, a man came along. He said: My father told me on the authority of my grandfather, saying: My father sent me to the Apostle of Allah (peace_be_upon_him) and said: Go to him and give him a greeting. So I went to him and said: My father sends you a greeting. He said: Upon you and upon your father be peace.