If any friend desire thee to be his surety, give him a part of what thou hast to spare; if he press thee further, he is not thy friend at all, for friendship rather chooseth harm to itself than offereth it. If thou be bound for a stranger, thou art a fool; if for a merchant, thou puttest thy estate to learn to swim.

Remains of Sir Walter Raleigh...: With the Addition of Some Letters Never Printed Before (ed. 1702)