Did the Prophet (peace be upon him) pray in a short-sleeved thobe (half sleeve)?

There is no evidence in the Sunnah that the Prophet, peace and blessings be upon him, ever wore a short-sleeved shirt (half-sleeve), neither in prayer nor otherwise. Rather, the sleeves of his shirt reached the wrist. Scholars such as Ibn al-Qayyim and al-Suyuti mentioned that shortening the sleeve to the wrist is desirable, and that lengthening wide sleeves is an innovation (bid'ah) and extravagance, and it goes against his Sunnah, because it is a form of ostentation. This does not mean that whoever wears short-sleeved clothing (half-sleeve) is going against the Sunnah, for this falls under the category of customary practices (sunan al-adah), in which a person follows the custom of their country's people as long as it does not contravene the Sharia.