I say, and with God's help: The Messenger of God (peace be upon him) said: "A man should not look at the private parts of a man, nor a woman at the private parts of a woman" in Sahih Muslim 1: 266. The private parts of a man are from his navel to beyond his knees; thus, the navel is not considered private, while the knee is private because the knee is a joint composed of the bones of the leg and thigh in a way that makes it indistinguishable, and the thigh is private while the leg is not. In cases of ambiguity, one must act with caution; since the forbidden and the permissible are present, the forbidden prevails. The Messenger of God (peace be upon him) said to Jarhad when his thigh was exposed: "Did you not know that the thigh is private?" in Sunan Abu Dawood 4: 40, and Sunan al-Tirmidhi 5: 110, which he deemed good, and in Sahih al-Bukhari 1: 145 as a suspended narration. From 'Umayr ibn Ishaq, he said: "I was with Abu Huraira, and he said to Al-Hasan ibn Ali: Show me the place where you saw the Messenger of God kiss you. He uncovered his navel, and he kissed it. Sharik said: If the navel were private, he would not have uncovered it" in Sahih Ibn Hibban 12: 405, and Musnad Abu Hanifa 1: 90. The private parts of a woman in front of non-mahram men are her entire body except for her face and hands, and the basis for this is the saying of Allah: {And let them not display their adornment except that which [ordinarily] appears thereof} [An-Nur: 31]. From Aisha (may Allah be pleased with her): "That Asma bint Abi Bakr entered upon the Messenger of God (peace be upon him) while she was wearing thin garments, so the Messenger of God turned away from her and said: O Asma, when a woman reaches the age of menstruation, it is not permissible for her to show anything except this and this, and he pointed to his face and hands" in Sunan Abu Dawood 4: 62.