Ishaq bin Bakr bin Madr إسحاق بن بكر بن مضر · The Book of Purification

"I saw Abu Hurairah performing Wudu' on the roof of the Masjid ans he said: 'I ate some tough cheese, so I performed Wudu' because of that. I heard the Messenger of Allah (ﷺ) commanding us to do Wudu' from that which has been touched by fire.'"

"O son of my sister, perform Wudu', for I heard the Messenger of Allah (ﷺ) say: 'Perform Wudu' from that which has been touched by fire.'"