Praise be to Allah.
Before we answer this question we should note an important point, which is that the basic principle regarding colours of clothes for men and women is that all colours are permissible except where there is a shar’i text forbidding a certain colour for men or women. There are shar’i texts which encourage the wearing of certain colours and forbid the wearing of other colours, such as the following:
Black: Umm Khaalid bint Khaalid said: “The Prophet (peace and blessings of Allaah be upon him) was brought some clothes, among which was a small black khameesah [garment]. He said, ‘Who do you think we should give this to?’ The people remained silent. Then he said, ‘Bring me Umm Khaalid,’ and she was carried to him. He took the khameesah in his hand and put it on her, and said, ‘May you live long and wear it out.’ There was a green or yellow mark on it, and he said, ‘O Umm Khaalid, this is sanaah (good),’ and sanaah is an Abyssinian word.” (Reported by al-Bukhaari). Jaabir (may Allaah be pleased with him) said: “I saw the Messenger of Allaah (peace and blessings of Allaah be upon him) on the day of the Conquest of Makkah, wearing a black turban.” (Reported by Muslim). ‘Aa’ishah (may Allaah be pleased with her) said: “I made a black burdah (cloak) for the Messenger of Allaah ( ) peace and blessings of Allaah be upon him), and he wore it, but when he sweated in it he detected the smell of wool on it, so he took it off, because he used to like pleasant smells.” (Reported by Abu Dawood. Al-Haakim (4/188) said: it is saheeh according to the conditions of the two shaykhs. Al-Dhahabi agreed with him. Shaykh al-Albaani said in al-Saheehah (5/168, no. 2136): It is as they said. Abu Dawood named a chapter in his Sunan “Bab fi’l-Suwaad (chapter on black clothes)”. The author of ‘Awn al-Ma’bood (11/126) said: The hadeeth indicates that it is permissible to wear black and that there is nothing makrooh in doing so).
Black is permissible for both men and women alike. One of the false innovations (bid’ah) connected to this colour is the practice of deliberately wearing black at times of bereavement, which also involves imitating the Christians. Shaykh Muhammad ibn Saalih al-‘Uthaymeen said (Fataawa Islamiyah, 3/313): “Wearing black at times of bereavement is a false symbol that has no basis. At times of bereavement people should do what is commanded in Islam, which is to say ‘Innaa Lillaahi wa inna ilayhi raaji’oon. Allaahumma ajirni fi museebati wa’khluf li khayran minhaa (Truly! To Allaah we belong and truly, to Him we shall return. O Allaah, reward me for my calamity and compensate me with something better than it).’ If a person says this with faith and the hope of reward, Allaah will reward him for that and will replace what he has lost with something better.” He also said: “Allocating certain clothes for mourning is an act of bid’ah (innovation) in our opinion, and because it could indicate that a person is discontent with the decree of Allaah.”
White: Abu Dharr (may Allaah be pleased with him) said: “I came to the Prophet (peace and blessings of Allaah be upon him) and he was wearing a white garment and was asleep. I came back to him (later), and he had woken up…” (Reported by al-Bukhaari in his Saheeh, in a chapter he called Baab al-Thiyaab al-Beed (Chapter on white clothes)). Al-Bukhaari reported that Sa’d said: “I saw on the left of the Prophet (peace and blessings of Allaah be upon him) and on his right two men wearing white clothes on the day of Uhud. I never saw them before or since.” These two men were Jibreel and Mikaa’eel, as al-Haafiz Ibn Hajar mentioned in al-Fath (10/295). White is a colour recommended (mustahabb) for the living to wear and for the dead to be shrouded in, as was stated in the hadeeth narrated by Ibn ‘Abbaas, who said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘Wear your white clothes, for they are the best of your clothes, and shroud your dead in them.’” (Reported by Abu Dawood and al-Tirmidhi; classed as saheeh by al-Albaani in Ahkaam al-Janaa’iz (p. 82)). White is also the preferred colour for men’s ihraam (special garments for Hajj), which consists of an izaar (lower garment) and a rida’ (upper garment).
Green: Abu Ramthah said: “I saw the Messenger of Allaah (peace and blessings of Allaah be upon him) wearing two green garments.” (Reported by al-Tirmidhi, who said, this is a ghareeb hasan hadeeth, and by al-Nisaa’i, 5224).
Red: It was reported that wearing pure red is forbidden for men, but not for women, because of the hadeeth of Ibn ‘Umar: “The Messenger of Allaah (peace and blessings of Allaah be upon him) forbade mafdam” (reported by Imaam Ahmad and Ibn Maajah, 3591). Mafdam is something that is filled with red safflower dye. According to the commentary of al-Sindi on Sunan al-Nisaa’i, mafdam is something that is filled with red. It was reported that if ‘Umar saw a man wearing a garment dyed red with safflower, he would pull him aside and say, “Leave this for the women.” (Reported by al-Tabari).
‘Abd-Allaah ibn ‘Amr said: “A man who was wearing two red garments passed by the Prophet (peace and blessings of Allaah be upon him) and greeted him with salaam, but the Prophet (peace and blessings of Allaah be upon him) did not respond.” (Reported by Abu Dawood and al-Tirmidhi, and classed as hasan by al-Bazzaar, who said: we know it only through this isnaad, which includes Abu Yahya al-Qattaat, who is a disputed figure).
There were several suggestions as to why men are forbidden to wear red, including the following:
because it is the dress of the kuffaar
because it is the adornment of women, so forbidding it is a way of discouraging the imitation of women
because it is vanity and does not befit a decent man to wear it
The prohibition applies only to garments that are dyed completely red. Garments that contain another colour such as white, black, etc. are not forbidden. This is how the ahaadeeth that speak about the red hullah should be interpreted, such as the hadeeth of al-Bara’ (may Allaah be pleased with him) who said: “The Prophet (peace and blessings of Allaah be upon him) was of average height. I saw him wearing a red hullah, and I have never seen anything better than it.” (Reported by al-Bukhaari, 5400). The Yemeni hullah usually has stripes of red and another colour, it is not pure red.
Ibn al-Qayyim, may Allaah have mercy on him, said: “The clothing (of the Prophet (peace and blessings of Allaah be upon him)): Abu’l-Waleed told us Shu’bah told us from Abu Ishaaq who heard al-Bara’ (may Allaah be pleased with him) saying: ‘The Prophet (peace and blessings of Allaah be upon him) was of average height. I saw him wearing a red hullah, and I have never seen anything better than it.’ The hullah consists of an izaar and a rida’ (lower and upper garments)… It is a mistake to think that it was pure red and not mixed with any other colour. The red hullah is two Yemeni garments woven with red and black stripes like all the other Yemeni garments… But pure red is emphatically forbidden. In Saheeh al-Bukhaari it is stated that the Prophet (peace and blessings of Allaah be upon him) forbade red saddlecloths (or blankets) … With regard to red garments in general and red broadcloth, etc., the issue is still under discussion, but it is very disliked (makrooh).” (Zaad al-Ma’aad, 1/139). And Allaah knows best.