Sayyiduna Uqbah bin Amir (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Do not enter upon women." It was asked: What is the ruling about the husband's brother? He (peace and blessings be upon him) said: "The husband's brother is death."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14837