Mishkat al-Masabih #2405

He reported God’s messenger as saying, “A man must not be alone with a woman, and a woman must travel only when accompanied by a man who is within the prohibited degrees.” A man said, “I have been enrolled for such and such an expedition, and my wife intends to go out to perform the pilgrimage.” He therefore told him to go and perform the pilgrimage along with his wife. Bukhari and Muslim.