Al-Kāfi - Volume 6 > Washing the Head
Hadith #3

أَحْمَدُ بْنُ مُحَمَّدٍ عَنِ الْقَاسِمِ بْنِ يَحْيَى عَنْ جَدِّهِ الْحَسَنِ بْنِ رَاشِدٍ عَنْ أَبِي بَصِيرٍ عَنْ أَبِي عَبْدِ اللَّهِ ( عليه السلام ) قَالَ قَالَ أَمِيرُ الْمُؤْمِنِينَ ( عليه السلام ) غَسْلُ الرَّأْسِ بِالْخِطْمِيِّ يَذْهَبُ بِالدَّرَنِ وَ يَنْفِي الْأَقْذَاءَ .

3. Ahmad ibn Muhammad from has narrated from al-Qasim ibn Yahya from his grandfather al-Hassan ibn Rashid from abu Basir who has said the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said that ’Amir al-Mu’minin has said, ‘Washing the head with marshmallow plant removes dirt and fine dust.’”