Answered by Shaykh Faraz Rabbani
Please can you give references for the rule that it is makrooh to pray salah in clothes that you wouldn’t go out in/appear in public in?
The Prophet (Allah bless him & give him peace) is reported to have said, “If you have two garments, then pray in them.” (Abu Dawud, and others) That is, rather than in merely one. There are other hadiths that confirm this meaning.
This is why Imam Nawawi (Allah have mercy on him) said in his Majmu`, confirming the words of Imam Shirazi in his Muhadhdhab, “Our scholars [i.e. the Shafi`is (Allah have mercy on them)] said, ‘It is recommended to pray in the best clothes one can find…”
Imam Haskafi (Allah have mercy on him) stated in his Durr al-Mukhtar
“(And it is disliked to pray in lowly clothes) that one wears at home… if one has others, otherwise it is not disliked.”
Imam Ibn Abidin (Allah have mercy on him) said in his commentary Radd al-Muhtar,
“It is stated in al-Bahr [of Ibn Nujaym]: ‘It was explained in Sharh al-Wiqaya as being that which one would wear at home, but would not go in them to respectable people. It appears that it is somewhat disliked.’”