Jeremiah 3:6

The Lord said also unto me in the days of Josiah, the king, an account which the prophet here inserts on account of the application. Hast thou seen that which backsliding Israel hath done? Israel being called apostasy outright to emphasize the seriousness of her defection. She is gone up upon every high mountain and under every green tree and there hath played the harlot, in committing idolatry or spiritual adultery, the sanctuaries of idols being located in such places.