Referring a buyer to another wholesaler's deal
I received an email from another wholesaler in my area and he is offering to pay a referral fee to me if I find a buyer for a few houses he has under contract.
I haven't done much business with him in the past so we aren't at the level of trust I would like to be at when dealing with verbal promises of referral fees. How can I protect my referral fee should I find him a buyer that closes on his property?