Al-Kāfi
Hadith 4462ـ أَحْمَدُ بْنُ مُحَمَّدٍ عَنْ عَلِيِّ بْنِ الْحَسَنِ عَنْ مُحَسِّنِ بْنِ أَحْمَدَ عَنْ يُونُسَ بْنِ يَعْقُوبَ قَالَ سَمِعْتُ أَبَا عَبْدِ الله (عَلَيْهِ السَّلاَم) يَقُولُ الْخَاتَمُ فِي فَمِ الصَّائِمِ لَيْسَ بِهِ بَأْسٌ فَأَمَّا النَّوَاةُ فَلا.
2. Ahmad ibn Muhammad from has narrated from Ali ibn al-Husayn from Muhsin ibn Ahmad from Yunus ibn Ya’qub who has said the following: “I once heard abu ‘Abd Allah (a.s.), say, ‘The presence of a signet in the mouth of a fasting person is not harmful, but a date-stone is.’”