Sahih Muslim Book 39, Hadith Number 6748.
Chapter : The believer is likened to the date-palm tree.
Ibn Umar reported that Allah’s Messenger (may peace be upon him) one day said to his Companions: Tell me about a tree which has resemblance with a believer. The people began to mention (different) trees of the forest. Ibn ‘Umar said: It was instilled in my mind or in my heart and it stuck therein that it implied the date-palm tree. I made up my mind to make a mention of that but could not do that because of the presence of the elderly people there. When there was a hush amongst them (after they had expressed their views), Allah’s Messenger (may peace be upon him) said: It Is the date-palm tree.