And through this chain of transmission, from Muhammad bin Ahmad bin Yahya, from Al-Amraki, from Ali bin Ja’far, from Musa bin Ja’far عليه السلام: I asked Imam عليه السلام about mats that are affected by urine - can prayer be performed on them if they dry without being washed? Imam عليه السلام said: "Yes, there is no harm."