Sahih Bukhari Volume 004, Book 056, Hadith Number 783.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 56. Virtues and Merits of the Prophets (PBUH) and his Companions
Narated By Ibn Umar : The Prophet used to deliver his sermons while standing beside a trunk of a datepalm. When he had the pulpit made, he used it instead. The trunk started crying and the Prophet went to it, rubbing his hand over it (to stop its crying).