But God came to Abimelech in a dream by night,.... Put a dream into his mind, by which he cautioned him against taking Sarah to be his wife; so careful was the Lord that no wrong should be done to such a godly and virtuous person, to which she was exposed through the weakness of her husband.
Aben Ezra wrongly interprets this of an angel, when it was God himself:and said unto him, behold, thou [art but] a dead man, for the woman which thou hast taken; that is, God would punish him with death, unless he restored the woman, whom he had taken, to her husband; not for any uncleanness he had committed with her, but for taking her without her free and full consent, and without inquiring more strictly into her relation to Abraham, and connection with him, and for his impure and unlawful desires after her, if persisted in:for she [is] a man's wife, or "married to an husband" ; and therefore it was unlawful in him to take her to be his wife.