One day when Ryokan returned to his hut he discovered a robber who had broken in and was in the process of stealing his few possessions. In the thief’s haste to leave, he left behind a cushion. Ryokan grabbed the cushion and ran after the thief to give it to him. He then wrote one of his most famous poems:
The thief left it behind:
at my window.
From Idries Shah‘s book The Way of the Sufi:
A thief entered the house of a Sufi, and found nothing there. As he was leaving, the dervish perceived his disappointment and threw him the blanket in which he was sleeping, so that he should not go away empty-handed.