The Messenger of Allah ﷺ forbade two ways of dressing and two ways of sitting.As for the two ways of dressing, they are praying in trousers with nothing else on, and a man praying in a single garment without draping part of it over his shoulder.As for the sitting, it is wrapping oneself in a single garment while drawing up the knees in such a way that one's private parts become visible, and sitting partly in the shade and partly in the sun.
عن رسول الله ﷺ أنه نهى عن لبستين، وعن مجلسين، أما اللبستان فتصلي في السراويل ليس عليك شيء غيره، والرجل يصلي في الثوب الواحد لا يتوشح به، والمجلس: أن يحتبي بالثوب الواحد فتبصر عورته، ويجلس بين الظل والشمس.
Narrated by Abu Dawud (636), Ibn Abu Shayba (25728), whose wording this is, and Hakim (4/272), all of them through the hadith of Abu Munib Ubaydullah Atiki, from Ubaydullah bin Burayda, from his father, who related it.Its chain is hasan because of Abu Munib, for Bukhari made critical remarks about him, while Nasai deemed him trustworthy, so he is acceptable when there is a foundation for his hadith. Hakim said nothing about him, but Dhahabi said, "Abu Munib was strengthened by Abu Hatim, and Nasai relied on him as evidence."