Muwatta Malik Book 8, Hadith 32
Yahya related to me from Malik from Ibn Shihab that Said ibn al-
Musayyab said that Abu Hurayra was asked, "May a man pray in one
garment?" He said, "Yes." The man then said to him "Do you do that?"
and he replied, "Yes, I pray in one garment while my clothes are on
the clothes-rack."
Yahya related to me from Malik from Ibn Shihab from Said ibn al- Musayyab from Abu Hurayra that some one asked the Messenger of Allah, may Allah bless him and grant him peace about praying in one garment. The Messenger of Allah, may Allah bless him and grant him peace, said, "Do you all have two garments?"
Yahya related to me from Malik that he had heard that Jabir ibn Abdullah used to pray in one garment.