´It was narrated that Salamah bin Al-Akwa said:` " I said: 'O Messenger of Allah(ﷺ), I go hunting wearing nothing but a single shirt. Can I pray in it?' He said: 'Fasten it to yourself even with a thorn.'"
Hadith Referenceسنن نسائي / كتاب القبلة / 766
Hadith Gradingالألبانی:حسن | زبیر علی زئی:إسناده حسن
766. Commentary: If the shirt (qamees) is long, reaching below the knees, so that during the performance of any pillar (rukun) the knees are not exposed from the front or back, then with this precaution one may pray in it, provided that the front collar is buttoned so that the awrah (private area) is not exposed from the front.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 766
Narrated Salamah ibn al-Akwa: I said: Messenger of Allah, I am a man who goes out hunting; may I pray in a single shirt? He replied: Yes, but fasten it even if it should be with a thorn.
Shaykh Umar Farooq Saeedi
632. Commentary: It is evident that what is meant here is the specific long shirt (qamees) of the Arabs. If there is no lower garment (shalwar) or sheet (chadar) beneath it, the prayer is still valid, provided that the ‘awrah (private parts that must be covered) is completely concealed. If there is a risk of exposure, then it has been commanded to tie it securely.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 632