Al-Kāfi - Volume 6 > The Under arms
Hadith #7

عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ سَهْلِ بْنِ زِيَادٍ عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ أَبِي نَصْرٍ عَنْ يُونُسَ بْنِ يَعْقُوبَ قَالَ بَلَغَنِي أَنَّ أَبَا عَبْدِ اللَّهِ ( عليه السلام ) رُبَّمَا دَخَلَ الْحَمَّامَ مُتَعَمِّداً يَطْلِي إِبْطَهُ وَحْدَهُ .

7. A number of our people have narrated from Sahl ibn Ziyad from Ahmad ibn Muhammad from ibn abu Nasr from Yunus ibn Ya’qub who has said the following: “I am informed that abu ‘ Abd Allah, ‘Alayhi al-Salam, enters the bathhouse only to apply lime paste to his underarms alone.’”