Salaat is worship of the Lord Almighty Allah (Subhanahu Wa Ta'ala). For this, apart from cleanliness (Taharah), we should also be particular about beauty and adornment. Allah (Subhanahu Wa Ta'ala) says in the Holy Quran:
O Children of Adam! Dress up decently every time you offer Prayer. And eat and drink but do not spend extravagantly because certainly He does not like the extravagant. Surah A’araaf (7:31)
For this reason, the Jurists (Fuqaha) have said that it is disliked that person should offer Salaat in such clothing which he/she wears while working in the house and would not prefer to wear those clothes while meeting somebody of stature.
Obviously, a person does not meet any person of stature and high rank in reverse clothing or does not meet the ‘Ulama and the pious people in such clothes. So, the Fuqaha have ruled it to be Mildly Undesirable (Makruh Tanzeehi).
As given in Raddul Muhtaar, Vol. 1, Kitab us Salaat, Pg No: 474.
Islam gives full permission to wear different kinds and different designs of clothes, but gives the limits also that the garment should be "Satir" i.e. it should cover the body appropriately. The lower body garment worn by men should not go below the ankle. There is a warning about this.
Translation: It has been narrated on the authority of Hadhrat Abu Hurairah (May Allah be well pleased with him) that the Holy Prophet (Sallallahu alaihi wa sallam) said: The part of the lower body garment below the ankles is in Hell. (Sahih Bukhari, Vol. 2)
Again in Sahih Bukhari itself, Vol. 2, Kitab Ul Libas, there is another Hadith narrated from Hadhrat Abu Hurairah (May Allah be well pleased with him) that the Holy Prophet (Sallallahu alaihi wa sallam) said: On the day of Qiyamah, Allah (Subhanahu Wa Ta'ala) does not even look at that person who kept his garment below his ankles out of pride.
In the light of these and such Hadith, the Fuqaha (Jurists) have ruled that it is Makruh (undesirable).
As given in Radd ul Muhtaar, Vol. 5.
Another advantage of keeping clothes above the ankles is that the garment remains clean of dirt and filth, as given in a lengthy Hadith in Musnad Ahmed (Hadith No: 22008). Consider a part out of it:
Translation: Listen! If you raise your garment, it will stay safer and cleaner.
We are careless about this and thus are missing out on this Sunnah. We ourselves should follow the Sunnah and invite our relatives, friends etc. to do the same.
Jeans or any other garment should not be so tight fitting that the parts of the body are outlined. Thus, it is better not to wear these kinds of garments.
And Allah (Subhanahu Wa Ta’ala) knows best.
Mufti Syed Ziauddin Naqshbandi Qadri,
[Professor, Islamic Law, Jamia Nizamia,
Founder/Director Abul Hasanaat Islamic Research Center]