What is the ruling on not writing down debt when lending to friends?

Allah guided His servants to document their debts in writing, as He says: "O you who have believed, when you contract a debt for a specified term, write it down." The command here is for recommendation, not obligation. If you trust your friends and their trustworthiness, you may lend to them without writing or witnessing. However, if you wish to document the debt out of fear of changes in their circumstances or their death, there is no blame upon you for doing so, in order to safeguard rights and prevent disputes.