From Sahih Bukhari (Hadith 61):
Narrated Ibn `Umar:Allah's Messenger (ﷺ) said, "Amongst the trees, there is a tree, the leaves of which do not fall and is like a Muslim. Tell me the name of that tree." Everybody started thinking about the trees of the desert areas. And I thought of the date-palm tree but felt shy to answer the others then asked, "What is that tree, O Allah's Messenger (ﷺ) ?" He replied, "It is the date-palm tree
Reference: Bukhari 61