question #3 Sahih Muslim 327a, Book 3, Hadith 62 : What is the significance of the Prophet Muhammad (ﷺ) specifying the use of three handfuls of water for washing the head?

The people contended amongst themselves in the presence of the Messenger of Allah (ﷺ) with regard to bathing. Some of them said: We wash our heads like this and this. Upon this the Messenger (ﷺ) said: As for me I pour three handfuls of water upon my head.