Question Summary:
What is the Sunnah clothing?

Question Detail:

 
My question is regarding what is Sunnah clothing and what isn't. Many people say that since the Prophet (SAW) did not particularly mention any clothing as Sunnah, we should stick to the culture around us, as long as the requirements are being met. Some shuyookh say that the Prophet simply stuck to his own culture, and so should we. Is there evidence of thobe, shalwar kameez, jubba, or kufi, turban being mandated as Sunnah from the early scholars? Also, I've heard how Imams are not allowed to wear shirt and pants and how Salah led by a person wearing shirt and pants is not accepted. Are these things true? 

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
There are two aspects to your Query,

We will look at each one individually.
Turban
Shaikhul Hadith Maulana Mohammed Zakariyya Khandalwi (R.A) has written the following in his commentary of "Shamaail Tirmithi", "Khasaail-e-Nabawi",
"The tying of the turban is a "Sunnate Mustamirrah" (perpetually adhered to Practice of Nabi صلى الله عليه و سلم). Nabi (صلى الله عليه و سلم) has conjoined tying of the turban upon us. It has been reported; "Tie the turban; it will increase you in forbearance". [Fathul-Bari]
It is reported in one hadith that Nabi (صلى الله عليه و سلم) said: "Wear the turban as it is a sign of Islam and distinguishes between a Muslim and non-Muslim". [‘Ayni]
Sayyiduna ‘Amr ibn Umayya Damri (Radiallahu Anhu) reports: I saw Nabi (صلى الله عليه و سلم) making masah of his leather socks and turban. [Sahihul-Bukhari Vol 1 Page 33]
Sayyiduna Huraith (Radiallahu Anhu) reports that Nabi (صلى الله عليه و سلم) addressed the people while wearing a black turban. [Sahih Muslim Vol 1 Page 439, Ibn Abi Shaibah Vol 8 Page 233]
Topi/Kufi (Headgear)
Ibn Umar (Radiallahu Anhuma) narrates that Nabi (صلى الله عليه و سلم) used to wear a white Topi. [Tabrani]
Abu Sheikh Reports from Ibn Abbas (Radiallahu Anhu) that Nabi (صلى الله عليه و سلم) had three Topis in his possession. [Bathlul -Majhood Vol 6 page52]
Nabi صلى الله عليه و سلم)) has said that a Muhrim (person in Ihram) must not wear a kurta, turban, pants and a "burnus" (specific type of Topi) (i.e. he will not wear these types of clothing). [Sahihul-Bukhari Vol 1 page 209. Vol. 2 page 864]
Sayyiduna Ali (Radiallahu Anhu) was seen wearing a white Egyptian Topi. [Tabaqaat Ibn Sa’d Urdu Vol 3 page 187]
It is thus learnt that people were in the habit of wearing the Topi in the time of Rasulullah.
Ibn-al- Arabi writes, "The Topi is amongst the clothing of the Ambiyaa and Pious ones. It protects the head and keeps the turban in place, which is Sunnat. The Topi should sit on the head and should not be standing like a dome. Should anyone feel the necessity of making holes in the Topi in order to keep the head cool and to let out steam, then this would be regarded as a means of treatment (i.e. this should not be done without necessity. [Faizul Qadeer vol. 5 pg. 247]
Kurta/Thobe (upper garment)
Nabi صلى الله عليه و سلم)) preferred the kurta over all other types of clothing.
Umm Salma (Radiallahu Anha) narrates that Nabi (صلى الله عليه و سلم) preferred the kurta over all other types of clothing.
The Ulama have attributed the preferability of the kurta to the following characteristics:
1. It conceals the body better than other forms of clothing such as the Chadar (a loose sheet that used to be worn) and lungi etc.
2. It does not cost very much and is so light that it represents no burden to the wearer.
3. Humility is indigent in its nature. [Jam’ul wasail Vol 1 page 107]
Sheikh Zakariyya (R.A) writes concerning the kurta that it is a wonderful concealer of the Satr (part of the body, the concealment of which is obligatory) while fulfilling the natural dictates of beauty and elegance that abound our choice of attire. [Khasaail-e-Nabawi page 36]
Abu Hurairah (Radiallahu Anhu) reports that Nabi (صلى الله عليه و سلم) would begin with the right side when wearing his kurta. (I.e. He would first place the right hand in the right sleeve) [Tirmizi Vol 1 page 306]
Ibn Abbas (Radiallahu Anhuma) reports that lengthwise the kurta of Rasulullah would be above his ankles while the sleeves would reach up to his fingers.
Allamah Munawi writes in his commentary of this hadith that it is learnt from the coupling of another narration with this one that "Above the Ankles" means the middle of the calf (halfway between the ankles and knees), just as it has been reported in one narration [Faizul Qadeer vol. 5 pg. 173]
Hazrat Sheikh Zakariyya (R.A) writes that Allamah Shaami has written that the kurta should be till the middle of the calf. [Khasaail page37]
If the kurta is quite short such as it just reaches the knees or even shorter then it would not be described as being above the ankles (hence falling out of the purview of the Hadith). The principle point of this interpretation is that it should be above the ankles but nevertheless close to it.
"Guard against lengthening your clothes (below the ankle) for such lengthening itself is an act of pride". [Abu Dawood – Mishkaat page169]
It is thus learnt that wearing the clothing below the ankles will be construed as an act of pride whether motivated by such intentions or not, yet people are unaware of this and explain away their wrongs by feeble excuses.
It is thus learnt that people in the time of Nabi (Sallallahu Alaihi Wasallam) were in the habit of wearing kurtas, Topi, turbans etc ^[1].
Some detail concerning the kurta can be gauged from the above narrations.
As for the second part of your query we must bear in mind that Rasulullah (Sallallahu alayhi Wasallam), Sahabah (Radiallahu Anhum) and the Ulama are our role-models. However, some of us would still opt for less than the ideal. If this is the case then we must avoid such clothing which would associate us with another religion. What is meant here is that if a dress is such that an onlooker associates that modality to some other religion or cult etc. then such dressing will not be permissible. 
It is permissible to wear shirts and pants. However, one should endeavour to adorn oneself with the Sunnah attire as explained above.
The position of the Imam is a noble one. Rasulullah lead Salah during his entire prophet-hood. An Imam should consider the lofty position of an Imam and dress accordingly to the Sunnah.
May Allah Ta’āla grant the entire Ummah the Tawfiq of following Nabi (Sallallahu Alayhi Wasallam) and the Salafe-Saaliheen (pious predecessors). May he save them from the imitation of the Jews and Christians. Aameen.
And Allah Ta’āla Knows Best
Bilal Ishaq (Issak)
Student Darul Iftaa
Leicester, England, UK
Checked and Approved by,
Mufti Ebrahim Desai.
 
[1] Taken from the book- Turban, Kurta, and Topee by Shaikhul-Hadith Maulana Fazlur-Rahman Saheb DB.
  فتاوى الهندية - (ج 5 / ص 333  دار الفكر  
وإسبال الإزار والقميص بدعة ينبغي أن يكون الإزار فوق الكعبين إلى نصف الساق وهذا في حق الرجال وأما النساء فيرخين إزارهن أسفل من إزار الرجال ليستر ظهر قدمهن إسبال الرجل إزاره أسفل من الكعبين إن لم يكن للخيلاء ففيه كراهة تنزيه كذا في الغرائب