Musnad Ahmad 30:133

Sufyan narrated to us, from al-Zuhri, from Sa’id, from Abu Hurayrah: A man said, "O Messenger of Allah, may one of us pray in a single garment?" He said, "Do all of you have two garments?" Abu Hurayrah said, "You have seen Abu Hurayrah praying in a single garment, while his garments were on the peg."