The Messenger of Allah (ﷺ) said, "Avoid (entering a place) in which are women (uncovered or simply to mix with them in seclusion)." A man from the Ansar said, "Tell me about the brother of a woman's husband." He replied, "The brother of a woman's husband is death."[Al- Bukhari and Muslim].

The Messenger of Allah (ﷺ) said, "No one of you should meet a woman in privacy unless she is accompanied by a Mahram (i.e., a relative within the prohibited degrees)."[Al-Bukhari and Muslim].

The Messenger of Allah (ﷺ) said, "The sanctity of the wives of Mujahidun (i.e., those who strive hard and fight in the way of Allah) for those who remain at home (i.e., those who do not go to the battlefield to fight Jihad) is like the sanctity of their own mothers. Anyone who remains behind to look after the family of a Mujahid and betrays his trust, will be made to stand on the Day of Resurrection before the Mujahid who will take away from his meritorious deeds whatever he likes till he is satisfied." The Messenger of Allah (ﷺ) turned toward us and said, "Now, what do you think (i.e., will he leave anything with him)?"[Muslim].

The Messenger of Allah (ﷺ) cursed those men who are effeminate, and women who imitate men.Another narration is: The Messenger of Allah (ﷺ) cursed men who copy women and cursed women who copy men.[Al-Bukhari].

The Messenger of Allah (ﷺ) cursed a man who puts on the dress of women, and a woman who puts on the dress of men.[Abu Dawud].

The Messenger of Allah (ﷺ) said, "There are two types of people who will be punished in Hell and whom I have not seen: men having whips like the tails of cows and they will be beating people with them, and, women who will be dressed but appear to be naked, inviting to evil; and they themselves will be inclined to it. Their heads will appear like the humps of the Bactrian camel inclined to one side. They will not enter Jannah and they will not smell its fragrance which is perceptible from such and such a distance."[Muslim].

I heard the Messenger of Allah (ﷺ) as saying: "Do not eat with your left hand, because Satan eats and drinks with his left hand."[Muslim].

The Messenger of Allah (ﷺ) said, "No person should eat and drink with his left hand for Satan eats with his left hand and drinks with his left hand."[Muslim].

I heard the Messenger of Allah (ﷺ) as saying: "Jews and Christians do not dye their hair, so act differently from them."[Al-Bukhari and Muslim].

Abu Quhafah, father of Abu Bakr (May Allah be pleased with them) was presented to the Messenger of Allah (ﷺ) on the day of the conquest of Makkah and his head and beard were snow white. The Messenger of Allah (ﷺ) said, "Change it (i.e., dye it and avoid black colour)."[Muslim].

The Messenger of Allah (ﷺ) forbade shaving a part of the head.[Al-Bukhari and Muslim].

The Messenger of Allah (ﷺ) saw a boy, some portion of whose head was shaved and some of it was left out. He prohibited them from that and said, "Shave the whole of it or leave the whole of it."[Muslim].

The Prophet (ﷺ) gave respite for three days to the family of Ja'far (after his martydom). Then he came and said, "Don't weep for my brother after this day." He said, "Bring all of my nephews to me." We were accordingly brought as if we were chickens. Then he said, "Call for me a barber." He directed him to shave our heads which he did.[Abu Dawud].

The Messenger of Allah (ﷺ) prohibited a woman from shaving her head.[An- Nasa'i].

A woman came to the Prophet (ﷺ) and said: "O Messenger of Allah! I have a daughter who had an attack of small pox and her hair fell off. Now I want to celebrate her marriage. Can I get her a wig?" Thereupon the Prophet (ﷺ) said, "Allah has cursed the maker and wearer of a wig."[Al-Bukhari and Muslim].

A similar narration was narrated on the authority of 'Aishah.

I saw Mu'awiyah (May Allah be pleased with him) during the Hajj (pilgrimage) standing on the pulpit. He took from the guard a bunch of hair, and said: "O people of Al-Madinah! Where are your scholars? (Why do they do not prohibit you) I heard the Prophet (ﷺ) prohibiting from using this (false hair) and saying, 'The people of Bani Israel were ruined when their women wore such hair."'[Al-Bukhari and Muslim]

The Messenger of Allah (ﷺ) cursed the maker and wearer of a wig and the tattooer and the one who is tattooed.[Al-Bukhari and Muslim].

Allah has cursed those women who practise tattooing and those women who have themselves tattooed, and those women who get their hair removed from their eyebrows and faces (except the beard and the mustache), and those who make artificial spaces between their teeth for beauty, whereby they change Allah's creation. A woman started to argue with him, saying: "What is all this?" He replied: "Why should I not curse those whom the Messenger of Allah (ﷺ) cursed and who are cursed in Allah's Book? Allah, the Exalted, has said in His Book:"And whatsoever the Messenger (Muhammad (ﷺ)) gives you, take it; and whatsoever he forbids you, abstain (from it)." (59:7)[Al-Bukhari and Muslim].

The Messenger of Allah (ﷺ) said, "He who does something contrary to our way (i.e., Islam) will have it rejected."[Muslim].