ScottyMacEsq : Thank you for using JustAnswer. I am researching your issue and will respond shortly.
ScottyMacEsq : This oral promise to pay you back when the rental house is sold would not be enforceable. It might as well be as though he has not made that promise. Ultimately it depends on his ability to pay.
ScottyMacEsq : You can enforce the claim against his estate, and you can have his daughter sign it in her role as executor of the estate (rather than personally).
ScottyMacEsq : But he could go bankrupt and get that released.
ScottyMacEsq : (and you would have nothing in return)
ScottyMacEsq : Collateral gives you that something that you cold keep if he did not pay it. Having the executor sign would give you an additional claim (especially in priority) against the estate.
ScottyMacEsq : But ultimately it depends on how much of a friend and how likely you think that repaying is. I would not say it's unreasonable, and you're the one with the money so you get to set the rules.
ScottyMacEsq : Hope that clears things up a bit. If you have any other questions, please let me know. If not, and you have not yet, please rate my answer AND press the "submit" button, if applicable. Please note that I don't get any credit for my answer unless and until you rate it a 3, 4, 5 (good or better). Thank you, XXXXX XXXXX luck to you!