Mukhtasar Muslim

Narrated Ibn Abbas (may Allah be pleased with them) that I heard the Prophet (peace and blessings of Allah be upon him) say in a sermon: "No man should be alone with a woman except when her mahram is with her. And no woman should travel except with a mahram relative." Then a man stood up and said, "O Messenger of Allah! My wife has set out for Hajj and my name has been registered in such-and-such army (i.e., I have been enlisted among the warriors)." The Prophet (peace and blessings of Allah be upon him) said, "Go and perform Hajj with your wife."