Is this the 1st time he will borrow from you? For me kasi kung 1st time i usually lend some basta small amount lang, being clear kung kelan nila ibabalik. Just think of it as a way to help someone in need (if he really is in need), which is a lot better than being in their shoes. If he doesn't pay up, then its a lesson learned. May karma naman yan.

But if you don't feel giving anything to him due to his track record, then just don't.