Maliks Muwatta Book 3, Hadith Number 75.

Section : Looking in the Prayer at What Distracts You from It.

Yahya related to me from Malik from Abdullah ibn Abi Bakr that a man from the Ansar was praying in a garden of his in Quff, one of the valleys of Madina, during the date season and the palms’ branches were weighed down with fruit on all sides. He looked at them and what he saw of their fruits amazed him. Then he went back to his prayer and he did not know how much he had prayed. He said, “A trial has befallen me in this property of mine.” So he went to Uthman ibn Affan, who was the khalifa at the time, and mentioned it to him and said, “It is sadaqa, so give it away in the paths of good.” Uthman ibn Affan sold it for fifty thousand and so that property became known as the Fifty.