28-7 (The author of the book narrated) my father - may God be pleased with him - narrated that Ali ibn Musa ibn Ja’far ibn Abi Ja’far al-Komandani quoted on the authority of Ahmad ibn Muhammad ibn Isa, on the authority of Abdul Aziz ibn al-Mohtadi, on the authority of Al-Ridha (s), “One must only wash the outside of the mouth with soap. The inside of the mouth does not get oily.”