Which Colours Are Prohibited in Islam?
Question

What is meant by “dyed with safflower (mu‘asfar)” in the hadith? Is it permissible to wear a green or beige garment? Is there any evidence to suggest that they are makruh?.
Praise be to Allah.What type of clothing is permitted?
 The basic principle with regard to clothing is that it is permissible because Allah, may He be exalted, says (interpretation of the meaning):
“He it is Who created for you all that is on earth. Then He Istawa (rose over) towards the heaven and made them seven heavens and He is the All-Knower of everything.” [Al-Baqarah 2:29] 
He has blessed us by giving us the means of clothing ourselves, as He says (interpretation of the meaning):
“O Children of Adam! We have bestowed raiment upon you to cover yourselves (screen your private parts, etc.) and as an adornment, and the raiment of righteousness, that is better. Such are among the Ayat (proofs, evidences, verses, lessons, signs, revelations, etc.) of Allah, that they may remember (i.e. leave falsehood and follow truth).” [Al-A‘raf 7:26]
The one who claims that a certain type or colour of clothing is haram is required to produce evidence to prove that. 
The scholars differed concerning the ruling on men wearing three colours : 

Pure red that is not mixed with any other colour . As for red that is mixed with another colour, they are agreed that it is permissible.
Clothing dyed with ‘usfur (safflower or carthamus tinctorius, a plant which gives a red colour). As for clothing that is dyed red with something other than safflower, it comes under the previous ruling.
Clothing dyed with saffron (a plant which gives a yellow colour). As for clothing that is dyed yellow with something other than saffron, the scholars are agreed that it is permissible.

Ruling on wearing clothing that is dyed with safflower
With regard to the ruling on wearing clothing that is dyed with safflower, the scholars differed concerning it and there are three opinions: 

That it is haram.

This is the view of the Zahiriyyah (literalists) and it is the opinion favoured by Ibn al-Qayyim.  
Their evidence is the report narrated by Muslim (2077) from ‘Abdullah ibn ‘Amr ibn al-‘As, who said: The Messenger of Allah (blessings and peace of Allah be upon him) saw me wearing two garments that had been dyed with safflower and he said: “These are garments of the disbelievers ; do not wear them.” 
According to another report, the Prophet (blessings and peace of Allah be upon him) said: “Did your mother tell you to do this?” I said: Should I wash them? He said: “No, burn them.” 
And Muslim narrated from ‘Ali (may Allah be pleased with him) that the Messenger of Allah (blessings and peace of Allah be upon him) forbade garments dyed with safflower. 

That it is makruh.

This is the view of the Hanafis and Malikis, and it is the view adopted by the Hanbalis, who said: The previous prohibition may be understood as meaning that it is makruh, because it is proven that al-Bara’ ibn ‘Azib (may Allah be pleased with him) said: I saw the Prophet (blessings and peace of Allah be upon him) wearing a red hullah (suit). (Narrated by al-Bukhari, 3551; Muslim, 2337) 

That it is permissible.

This is the view of the Shafi`is. (Al-Majmu‘, 4/450; al-Mughni, 2/299; al-Muhalla, 4/69; Tahdhib Sunan Abi Dawud, 11/117; Hashiyat Ibn ‘Abidin, 5/228) 
What appears most likely to be correct – and Allah knows best – is the opinion that it is haram, because the basic principle concerning prohibition is that it means that a thing is haram. With regard to the Prophet (blessings and peace of Allah be upon him) wearing red, it does not mean that his red garment had been dyed with safflower; rather it was dyed red with something other than safflower. (See: Ma'alim al-Sunan, 4/179) 
Ruling on clothes dyed with saffron
With regard to clothing dyed with saffron, the scholars differed concerning it and there are also three opinions, the most correct of which is that of the Shafi`is, which was also narrated by the Hanbalis, that it is haram for men to wear garments dyed with saffron. 
The evidence for that is the report narrated from Anas (may Allah be pleased with him) who said: The Messenger of Allah (blessings and peace of Allah be upon him) forbade men to dye their clothes with saffron. (Narrated by al-Bukhari, 5846; Muslim, 2101) 
Shaykh Ibn ‘Uthaymin (may Allah have mercy on him) said: 
“The correct view is that wearing clothing dyed with safflower is haram for men, and the same applies to clothing dyed with saffron.” (Ash-Sharh al-Mumti‘, 2/218) (See: at-Tamhid, 2/180; al-Insaf, 1/481; al-Muhalla, 4/76; al-Majmu‘, 4/440; Hashiyat Ibn ‘Abidin, 5/228; al-Mughni, 2/299)
Which colour is forbidden for men?
With regard to clothing of other colours , the scholars did not differ concerning the permissibility thereof; rather it was narrated that there was consensus on that. For example: 
An-Nawawi said in al-Majmu‘, 4/337: 
“It is permissible to wear white, red, yellow, green, striped and other colours of clothing, and there was no difference of opinion concerning that, and none of them are makruh.”
It says in al-Mawsu‘ah al-Fiqhiyyah, 6/132-136: 
“The jurists agreed that it is mustahabb to wear white clothing… 
The jurists agreed that it is permissible to wear yellow so long as it is not dyed with safflower or saffron.” 
Can women wear coloured clothes?
It is also permissible for women to wear whatever colours they like , so long as they do not display themselves in front of non-mahram men. Those scholars who spoke about the prohibition on wearing clothing dyed with safflower and saffron limited that to men only. 
Ibn ‘Abd al-Barr said in at-Tamhid, 16/123: 
“With regard to women, there is no difference of opinion among the scholars that it is permissible for them to wear clothing dyed various shades of red or pink.”
To sum up, green and beige are colours that it is permissible to wear, and there is nothing to suggest that they are haram, unless that is the result of dyeing with safflower or saffron. If that is the case, then it becomes haram to wear it, for men only. This is the most correct of the scholarly opinions. 
For more, please see this category: Rulings on Dress
And Allah knows best.