Al-Lu'lu Wal-Marjan 1792 — The Book About the Characteristics of the Hypocrites and Orders Concerning Them.

Ibn 'Umar Narrated from:

Allâh's Messenger صلى الله عليه وسلم 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. The others then asked, "Please inform us, what is that tree, O Allâh's Messenger?" He replied, "It is the date-palm tree." ( Sahîh Al-Bukhârî, Hadîth No. 59, Vol. 1)