With a trusted friend, even actions that seem hurtful ultimately turn out to be beneficial. A well-timed reprimand from someone who loves you can guide you to a better course of action. An enemy, however, should not be trusted. Even if he appears to offer love and support, he will ultimately lead you astray. This idea is reflected in the words of the prophets who rebuke the Israelites for putting their trust in other nations, such as Assyria and Egypt, instead of Hashem (God). Ultimately, they were let down by their enemies who determined they had nothing more to gain from the Jewish people.
Source: Israel in the News