Yes it is Sunnah to wear trousers to the middle of the shin. It is narrated in multiple authentic Hadith.
عَنِ ابْنِ عُمَرَ، قَالَ: مَرَرْتُ عَلَى رَسُولِ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ وَفِي إِزَارِي اسْتِرْخَاءٌ، فَقَالَ: «يَا عَبْدَ اللهِ، ارْفَعْ إِزَارَكَ»، فَرَفَعْتُهُ، ثُمَّ قَالَ: «زِدْ»، فَزِدْتُ، فَمَا زِلْتُ أَتَحَرَّاهَا بَعْدُ، فَقَالَ بَعْضُ الْقَوْمِ: إِلَى أَيْنَ؟ فَقَالَ: أَنْصَافِ السَّاقَيْنِ
(Sayidina) Ibn Umar narrated that, I passed by Allah’s Messenger ﷺ and my waist-wrapper (Izaar) was long. He ﷺ said, ‘Abdullah, raise your waist-wrapper (Izaar).’ So I raised it. Then he ﷺ said, ‘Raise it further.’ So I raised it further and I continued to pay attention to it afterwards. Thereupon some of the people said, To what extent? He replied, To the middle of the shins. (Sahih Muslim, 2086 – 47).
عَنْ حُذَيْفَةَ قَالَ: أَخَذَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ بِعَضَلَةِ سَاقِي، أَوْ سَاقِهِ، فَقَالَ: «هَذَا مَوْضِعُ الإِزَارِ، فَإِنْ أَبَيْتَ فَأَسْفَلَ، فَإِنْ أَبَيْتَ فَلَا حَقَّ لِلإِزَارِ فِي الكَعْبَيْنِ»: هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ
(Sayidina) Hudhaifah said, The Messenger of Allah ﷺ took hold of my calf – or his calf- then he ﷺ said, ‘This is the place of the Izaar, and if you must lower it, then the Izaar has no right to be at the ankles.’ (Sunan al-Tirmidhi 1783, Hasan Sahih).
The narrations above clearly demonstrate that the Sunnah of the Prophet (peace be upon him) was to wear the Izar (waist-wrapper) to mid-shin. There are numerous other narrations that establish this point too. Many books of Shamail have devoted chapters to the waist-wrapper of the Holy Prophet (peace be upon him) and narrate Hadith regarding this issue.
والسنة جعله إلى نصف الساقين
And the Sunnah is to have it (the Izaar) to the middle of the shins. (Imam Abd al-Ra’oof al-Munawi, Fayd al-Qadeer).
Unfortunately, many people are ignorant of this Sunnah and mock people who practice it. This is incredibly dangerous. Mocking a Sunnah of the blessed Prophet (peace be upon him) is Kufr. Not only is it incredibly sinful but jeopardises one’s Iman. Often this abhorrent misguidance is a result of a sectarian mindset. People see members of a group doing something and assume it is wrong without any consideration for the source of such a practice. This is one of many staggering harms of sectarianism.
And Allah Most High knows best.
– Answered by Shaykh Noorud-deen Rashid (05.01.2022)
Is it Sunnah to eat sittings on your knees?