It has been reported that a man had a palm-tree and while collecting the dates, some of them would fall in the neighbors' yard where a poor man lived. His children would pick up those dates and the owner would come to snatch away the dates from their hands and mouths. The poor man complained to the Prophet. The Prophet therefore asked the palm-tree from the owner in exchange of a tree in paradise but the owner refused. Another man who heard the proposal of the Prophet asked him if he would promise to him the same thing if he would get the palm-tree. The Prophet answered affirmatively. So the man was able to get the palm-tree in exchange of forty palm-tree of his. Finally the Prophet gave the palm-tree to the poor man and his children. This story has been mentioned as the cause of revelation for sura al-Layl in several Muslim sources.
With prayers for your success.