Mukhtasar Bukhari (Abridged) 1868 — No man should be alone

Narrated by Sayyiduna Uqbah bin Amir (may Allah be pleased with him): The Messenger of Allah (peace and blessings of Allah be upon him) said: "Avoid going to women (in seclusion)." An Ansari man said, "What about the brother-in-law?" The Prophet (peace be upon him) said: "The brother-in-law is death (i.e., one should be even more cautious of him)."