It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that once the Noble Prophet (peace and blessings be upon him) said: "There is a tree whose leaves do not fall, and it is like a Muslim. Tell me, which tree is that?" People began to think of various trees in the forest. In my heart, I thought it could be the date palm tree. After a little while, the Noble Prophet (peace and blessings be upon him) himself said: "It is the date palm tree." I mentioned this to Sayyiduna Umar (may Allah be pleased with him), and he said: "At that moment, your speaking up would have been more beloved to me than such and such thing."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 6468