Al-Kāfi - Volume 4 > A Fasting Person’s Use of Chewing Gum
Hadith #2

2ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ مُحَمَّدِ بْنِ الْحُسَيْنِ عَنْ عَلِيِّ بْنِ الْحَكَمِ عَنِ الْعَلاءِ بْنِ رَزِينٍ عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ قَالَ قَالَ أَبُو جَعْفَرٍ (عَلَيْهِ السَّلاَم) يَا مُحَمَّدُ إِيَّاكَ أَنْ تَمْضَغَ عِلْكاً فَإِنِّي مَضَغْتُ الْيَوْمَ عِلْكاً وَأَنَا صَائِمٌ فَوَجَدْتُ فِي نَفْسِي مِنْهُ شَيْئاً.

2. Muhammad ibn Yahya has narrated from Muhammad ibn al-Husayn, from Ali ibn al-Hakam from al-‘Ala’ ibn Razin from Muhammad ibn Muslim who has said the following: “Abu Ja‘far, ‘Alayhi al-Salam, once said to me, ‘O Muhammad, never chew chewing gum because I today did so when I was fasting and I found something from it in my soul.’”