Al-Kāfi - Volume 6 > The Black Dye and Woad
Hadith #3

ابْنُ مَحْبُوبٍ عَنِ الْعَلَاءِ بْنِ رَزِينٍ عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ قَالَ رَأَيْتُ أَبَا جَعْفَرٍ ( عليه السلام ) يَمْضَغُ عِلْكاً فَقَالَ يَا مُحَمَّدُ نَقَضَتِ الْوَسِمَةُ أَضْرَاسِي فَمَضَغْتُ هَذَا الْعِلْكَ لِأَشُدَّهَا قَالَ وَ كَانَتِ اسْتَرْخَتْ فَشَدَّهَا بِالذَّهَبِ .

3. Ibn Mahbub has narrated from al-‘Ala’ ibn Razin from Muhammad ibn Muslim who has said the following: “I once saw abu Ja‘far, ‘Alayhi al-Salam, chewing gums and he (the Imam) said, ‘O Muhammad, woad has loosened my molar teeth so I chew gums to strengthen them . 5 His teeth had become loose so he tied them with gold.”