Ibn Majah

Benefits and Issues:
➊ The translation of (sarawil) as either "shalwar" or "pajama" is correct in both ways, because it is the same garment with a difference in its style of making.

➋ The fact that the Messenger of Allah (sallallahu alayhi wa sallam) bought or expressed the intention to buy a shalwar is evidence that this is a permissible garment. However, in any authentic hadith, there is no mention of the Prophet (sallallahu alayhi wa sallam) actually wearing a pajama.

➌ It is permissible for men to wear a shalwar, because the Prophetic instruction is:
“If one does not find an izar (lower garment) at the time of donning ihram, he may wear sarawil (shalwar or pajama).” (Sunan Ibn Majah, Book of Manasik, Chapter: Sarawil and Khuffayn for the Muhrim if he does not find an Izar or sandals, Hadith: 2931)
If, in a state of necessity during ihram, a man is allowed to wear a shalwar, then it is even more permissible to wear a shalwar or pajama on ordinary days.