Sahih Bukhari, Chapter: Obligatory Charity Tax (Zakat)

The Prophet said, "A man from Bani Israel asked someone from Bani Israel to give him a loan of one thousand Dinars and the later gave it to him. The debtor went on a voyage (when the time for the payment of the debt became due) but he did not find a boat, so he took a piece of wood and bored it and put 1000 diners in it and threw it into the sea. The creditor went out and took the piece of wood to his family to be used as fire-wood." (See Hadith No. 488 B, Vol. 3). And the Prophet narrated the narration (and said), "When he sawed the wood, he found his money."