Where can I find a loan repayment contract?

I lent a buddy of mine some money, a little over $2,000. I did this as a personal favor. After thinking it over I thought it would be a good idea to have some kind of contract in place. I am not charging interest, but I do want him to be legally bound to repay the loan. I’m looking for a simple loan repayment contract or something of the sort. Anyone know where I can find something like this? Thanks!