What is the Maliki evidence for their saying regarding the reprehensibility of the imam not praying in a cloak (ridaa'), and do those who permit prayer in loose trousers that do not reveal the 'awrah have evidence for that?

According to the Malikis, it is disliked for the Imam to omit wearing a cloak (rida') during prayer. Some of them justified this by stating that it is a remnant of the practice of the people of Lut. Prayer is valid when performed in trousers (sarawil) that cover the 'awrah. It is stipulated that the garment must not be light to the extent that it describes or reveals [the body underneath]. Prayer performed solely in trousers with the upper body uncovered is valid according to most scholars, contrary to the Hanbalis, who stipulate covering the shoulders based on the hadith: "No man should pray in a single garment with nothing on his shoulders."