Abu Salama bin 'Abdur Rahman أبو سلمة بن عبد الرحمن بن عوف · The Book on Purification

I was with the Prophet on a journey. The Prophet had to relieve himself, so he went far away."

Allah's Messenger said: "If it were not that it would be difficult on my nation, then I would have ordered them to use the Siwak for each prayer."

'I heard Allah's Messenger saying: 'If it were not that it would be difficult on my nation then, I would have ordered them to use the Siwak for each prayer and to delay the Isha prayer until the third of the night.'"He said: Zaid bin Khalid wouId attend the prayer in the Masjid and his Siwak would be on his ear in the location of the pen on the ear of a writer. He would not get up to pray…

Allah's Messenger said: "Wudu is (required) from what fire has touched, even if it be a piece of cheese."