What is impermissible in men's clothing
10-4-2017 | IslamWeb
Question:
Are we allowed to wear anything unless it has been stated otherwise? Are we allowed to fold and stitch our thawbs at the bottom [the end of the thawb], and is this considered tucking one's clothes? What is a man not allowed to wear?
Answer:
All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad 
is His slave and Messenger.
Both men and women are permitted to wear whatever clothes they wish with the exception of what has been confirmed to be forbidden in the Sharia, because permissibility is the principle in clothing, not prohibition, as has been stated by the scholars.
Shaykh Ibn 'Uthaymeen 
said:
“I would like to mention a useful rule in this context, which is that all clothes are permissible in principle unless there is evidence that it is forbidden. Allah says (what means): {O children of Adam, We have bestowed upon you clothing to conceal your private parts and as adornment. But the clothing of righteousness - that is best. That is from the Signs of Allah that perhaps they will remember.} [Quran 7:26]
Allah also says (what means): {Say, ‘Who has forbidden the adornment of Allah which He has produced for His servants and the good [lawful] things of provision?’ Say, ‘They are for those who believe during the worldly life [but] exclusively for them on the Day of Resurrection.’ Thus do We detail the verses for a people who know.} [Quran 7:32]
The ruling on what men and women wear should be based on this rule; so we say that in principle it is lawful unless there is evidence for its prohibition…”
As regards what is forbidden for a man to wear, then the Sharia forbids men from wearing silk and gold, what resembles the dress of women or dissolute people, as well as Libaas ash-Shuhrah (uncommon clothes worn to gain notice or fame).
For more benefit, please refer to fatwa 87818.
The fatwa of the Standing Committee reads:
“The basic principle with regard to clothes is that they are permissible because they are among the matters of custom and habit; Allah says (what means): {Say, ‘Who has forbidden the adornment of Allah which He has produced for His servants and the good [lawful] things of provision?’}; except those which authentic religious texts have definitely forbidden or disliked, such as gold and silk for men, wearing clothes that shape the ‘Awrah (parts of the body that must be covered in public) because of it being transparent showing the color of the skin underneath or because of it being tight and thus shaping the ‘Awrah, as in this case it has the same ruling as revealing the ‘Awrah, which is forbidden, or the clothes that are peculiar to the non-Muslims, as these are forbidden to wear by both men and women…”
As regards the issue of tucking (folding up) clothes outside of the prayer, then there is nothing wrong in doing so whether it be by sewing it or otherwise.
With regard to the tucking of clothes while praying, then if the garment originally was above the ankles before tucking it and then a person tucks it to perform the prayer, then this tucking is forbidden in the Sunnah. The Prophet said, “And I was ordered not to fold back clothing or hair.” [Muslim]
The fatwa of the Standing Committee, on folding up the pants in prayer, reads, “If this folding up is done for the prayer, then it is forbidden.”
However, if one's garment originally was below the ankles before folding it, and then when he wanted to pray, he folded it up, then folding the clothes above the ankles is permissible for men in principle, and wearing clothes below the ankles is forbidden both in and outside the prayer according to the view of many scholars. So if he folds it up above the ankles, then he has done something that is permissible in principle.
Allah knows best.