Sahih Bukhari Volume 001, Book 003, Hadith Number 072.
Narated By Ibn 'Umar : We were with the Prophet and a spadix of date-palm tree was brought to him. On that he said, "Amongst the trees, there is a tree which resembles a Muslim." I wanted to say that it was the date-palm tree but as I was the youngest of all (of them) I kept quiet. And then the Prophet said, "It is the date-palm tree."