Sayyidah Aishah (may Allah be pleased with her) said that he (peace and blessings be upon him) would wash his head with khitmi; when he (peace and blessings be upon him) was junub, that would suffice him and he would not pour water over it.
(b) If this narration is established, it is to be understood as the case where the khitmi was predominant over the water and he (peace and blessings be upon him) washed his head with the intention of the ritual bath for janabah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 864