What did the Prophet (saw) say about a man who asked another man for a loan of one thousand Dinars and didn't have any witnesses?
      Narrated Abu Huraira:                          The Prophet said, "An Israeli man asked another Israeli to lend him      one thousand Dinars. The second man required witnesses. The former      replied, 'Allah is sufficient as a witness.' The second said, 'I want      a surety.' The former replied, 'Allah is sufficient as a surety.' The      second said, 'You are right,' and lent him the money for a certain      period. The debtor went across the sea. When he finished his job, he      searched for a conveyance so that he might reach in time for the      repayment of the debt, but he could not find any. So, he took a piece      of wood and made a hole in it, inserted in it one thousand Dinars and      a letter to the lender and then closed (i.e. sealed) the hole tightly.     He took the piece of wood to the sea and said. 'O Allah! You know well     that I took a loan of one thousand Dinars from so-and-so. He demanded      a surety from me but I told him that Allah's Guarantee was sufficient      and he accepted Your guarantee. He then asked for a witness and I told     him that Allah was sufficient as a Witness, and he accepted You as a      Witness. No doubt, I tried hard to find a conveyance so that I could      pay his money but could not find, so I hand over this money to You.'      Saying that, he threw the piece of wood into the sea till it went out      far into it, and then he went away. Meanwhile he started searching for     a conveyance in order to reach the creditor's country.      One day the lender came out of his house to see whether a ship had      arrived bringing his money, and all of a sudden he saw the piece of      wood in which his money had been deposited. He took it home to use for     fire. When he sawed it, he found his money and the letter inside it.      Shortly after that, the debtor came bringing one thousand Dinars to      him and said, 'By Allah, I had been trying hard to get a boat so that      I could bring you your money, but failed to get one before the one I      have come by.' The lender asked, 'Have you sent something to me?' The      debtor replied, 'I have told you I could not get a boat other than the     one I have come by.' The lender said, 'Allah has delivered on your      behalf the money you sent in the piece of wood. So, you may keep your      one thousand Dinars and depart guided on the right path.' "