It is narrated from Sayyiduna Khuzaymah bin Thabit (may Allah be pleased with him), the man of the two testimonies (Sahib al-Shahadatayn), that the Messenger of Allah (peace and blessings be upon him) said: "Indeed, Allah is not shy of the truth. Do not approach women in their backsides."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3719