Reference: Fataawa Noor ‘alad-Darb – Question No.6434, Page 262, Volume 12
Question: What is the story of the tree trunk by which the Messenger (sal-Allaahu ‘alayhi wa sallam) used to deliver the khutbah, and when the Messenger (sal-Allaahu ‘alayhi wa sallam) left it for a while, it began to make a sound yearning [for him to return]?
Response: The story is as the questioner has mentioned, that:
«The Messenger of Allaah (sal-Allaahu ‘alayhi wa sallam) used to deliver the khutbah by the trunk of a tree, so when the mimbar was established and he adopted that [as the place from which to deliver the khutbah], the tree trunk began to make a sound yearning [for him to return]. So he went over to it and wiped his hand over it [s if to calm/sooth it].» – transmitted by al-Bukhaaree.
And this was from amongst the miracles of the Messenger (sal-Allaahu ‘alayhi wa sallam), and it wasn’t the first nor the last, and nor was it the biggest of them.