Maybe, maybe not. The first question is whether you had a contract. Contracts require consideration, i.e. quid pro quo. The normal consideration for a loan is the payment of interest in addition to repayment of the loan amount, but you make no mention of that. What consideration is your friend getting in exchange for the loan? If nothing, I don't think you have a valid contract, and you must repay your friend, period.
If your friend is getting consideration for the loan (i.e. you drove him to work for 3 weeks, you loaned him the use of your tennis racket, you stopped singing that annoying song all the time, etc.), the answer will probably depend on what the Court finds were the terms of your agreement. Presumably, you will argue that the terms were that you would repay him only when you got your inheritance, while the lender will probably claim that you were to repay when you got your inheritance, but in no event longer than six months (or 8 months, or 12 months, etc.) Where no time for performance is agreed upon in a contract, the Court will imply a reasonable time. I don't know how long you have owed the money, but, unless you provided your friend with legitimate consideration, and unless the two of you specifically contemplated that your friend might never get repaid or might not get repaid for years, depending on a contingency which neither of you control (getting your inheritance), I doubt that the Court will think that holding up the money indefinitely, with no end in sight, was reasonable. My feeling is that, if it has only been two weeks, the Court might think it reasonable for your friend to wait a little longer, but if your friend has already been waiting for six months, I don't think a Court will think it reasonable that he be forced to wait any longer, and will enter judgment against you....
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