Answered by Shaykh Abdul-Karim Yahya, SunniPath Academy Teacher
What is the position of folding the trousers above the ankles for prayer? Does it invalidate the prayer? What about folding other clothing before or during the prayer? What is the position of the other schools on this ? I have read on this site about outside prayer but what about in the prayer?
In The Name of Allah, Most Merciful and Compassionate
It is offensive to draw together ones clothing [including pants] during the prayer, by folding or tucking them up for example, or to enter the prayer with ones garment like this. The proof of this is the prophetic tradition: “I have been ordered to prostrate on seven bones and to neither gather a garment nor hair.” The wisdom behind this is that it prevents the clothing and hair from prostrating along with one and it is an appearance which does not conform with submissiveness and humbleness.
However gathering one’s garment does not invalidate the prayer as long as one does not make three consecutive motions. I am unaware of the positions of the other schools, but this is the ruling according to the Shafi’i School. And Allah knows best and He alone gives success (tawfiq).
 Related by Bukhari and Muslim [No. 490].
 See: Ibn Hajar al-Haytami, Hawashi al-Sharwani Wa Ibn Qasim al-Abbadi ‘Ala Tuhfah al-Muhtaj Bisharh al-Minhaj (Beruit, Dar Ihya’ al-Turath al-‘Arabi), 2:162.