Sahih Al Bukhari Hadith Number 2430 

Narrated ‘Abdur-Rahman bin Hurmuz: Abu Hurairah (ra) said, “Allah’s Messenger (peace be upon him) mentioned an Israeli man.” Abu Hurairah then told the whole narration). (At the end of the narration it was mentioned that the creditor) went out to the sea, hoping that a boat might have brought his money. Suddenly he saw a piece of wood and he took it to his house to use as firewood. When he sawed it, he found his money and a letter in it. [See hadith No. 2291 for details]

45  Lost Things Picked up by Someone (Luqatah)
Hadith number 2430
Volume no 3
Chapter: 5 (If someone finds a thing in the sea)