Hadith 28-7

حَدَّثَنا أَبي‏ رَضِىَ اللهُ عَنْهُ قالَ: حَدَّثَنا عَلِىِّ بْنِ مُوسَى بْنِ جَعْفَر بْنِ أَبي جَعْفَر الكمندانِي، عَن‏مُحَمَّدِ بْنِ عِيسَى، عَن عَبْدُالْعَزِيز بْنِ المُهْتَدِي عَنِ الرِّضا عَلَيْهِ السَّلامُ قالَ إِنَّمَا يُغْسَلُ بِالأُشْنَانِ خَارِجُ الْفَمِ فَأَمَّا دَاخِلُ الْفَمِ فَلا يَقْبَلُ الْغَمَرَ.

(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’ (a.s.), “One must only wash the outside of the mouth with soap. The inside of the mouth does not get oily.”