Source: http://seekersguidance.org/
The color most pleasing to Prophet Muhammad (Allah’s peace and blessings be upon him) was green, while some said it was white. With respect to clothing, the Prophet (peace be upon him) encouraged men to wear white in numerous hadiths. Thus, according to the sunnah, it is preferred to wear white, as well as black and green. [Ibn Abidin, Radd al-Muhtar]
While wearing a green turban is not a specific sunnah, wearing green garments in general is from the sunnah, so one could wear a green turban to fulfill that.
It is important to note that the Prophet (Allah’s peace and blessings be upon him) himself wore different types of clothing from different places, and of different colors and designs, not just one style or color, though there would be nothing wrong if one chose to did this.
On Green Being the Favorite Color
Anas in Malik (Allah be pleased with him) is reported to have said,
“The most beloved of colors to the Messenger of Allah (Allah’s peace and blessings be upon him) was green.” [Tabarani, Mu’jam al-Awsat; al-Bazzar, Musnad]
Although this hadith by itself is weak in its chain, it is strengthened by a corroborating narration in which Anas and a group of people went out to a plot of land covered in vegetation, and so someone exclaimed, “How beautiful is this greenery!” Thereafter, Anas reminisced that, “We used to say that the Prophet’s (Allah’s peace and blessings be upon him) favorite color was green.” [al-Bayhaqi, Shu’ab al-Iman]
The main reason that scholars cite for this preference is that green will be the main color of the clothing of the people in Paradise [Qur’an 18:31]. It is also reported that the Prophet (peace and blessings be upon) used to like to gaze at the beauty of natural greenery.
The Virtue of White Clothing
The Prophet (peace be upon him) said: “Wear white from amongst your clothes, for indeed they are amongst the best clothes you have, and shroud your dead in them (also).” [Abu Dawud, Ibn Majah and Tirmidhi with variation in wording]
This does not make it an obligation, but it is a strong encouragement and a sunnah. It is the most preferred color to wear for men [Sayyid Ali Zada, Sharh Shir’atul Islam].
Based on this hadith, some scholars such as Ibn al-Qayyim inferred that the Prophet’s favorite color was white, peace and blessings be upon him [Ibn al-Qayyim, Zad al-Ma’ad].
The Green Turban: Is it Specifically a Sunnah?
The green turban itself is not a specific sunnah, in that we have no report that the Prophet (peace and blessings be upon him) wore it. However, generally wearing green clothes is a sunnah. [Ibn Abideen, Radd al-Muhtar; Shaykhi-Zada, Majma’ al-Anhur]
It is reported in the Musannaf of Ibn Abi Shayba however, that some Companions were seen wearing turbans of various colors, one of them being green.
Al-Kattani quotes Imam al-Suyuti as saying, “This green turban is not [prescribed] from the Sacred Law itself, nor from the Sunnah, and was not around [as a specific dress] in the early period [of Islam]. It was only begun [as a distinct practice] in the year 763 hijri by the order of [Sultan] al-Ashraf Sha’ban ibn Hasan [to those of the Prophetic Household, so that it might distinguish them from others out of respect].”
He then quotes al-Khadimi from al-Tariqa al-Muhammadiya, saying “This sign is a permissible innovation; the one who is not a Sharif [ie. Sayyid, from Ahl al Bayt] should not be prevented from wearing it, and a Sharif who leaves it should not be ordered to wear it…” [al-Kattani, al-Di’amah fi Ahkam Sunna al-‘Imama]
This returns back to the custom of one’s land. Today, one’s choosing a green turban can be based on the virtues of wearing the color green as a sunnah, or seeking to emulate those of prophetic lineage or spiritual learning who wear it in our times. And Allah knows best.