Musannaf Ibn Abi Shayba 1:771

Abu Bakr narrated to us, he said: Abu al-Ahwas narrated to us, from Abu Ishaq, from al-Harith ibn al-Azma', he said: Abdullah said: Whoever washes his head with marshmallow (khatmi) while he is in a state of major ritual impurity (junub), he has fulfilled the washing.