Exodus 30:19 "And Aaron and his sons will use it to wash their hands and feet"

Does your mother remind you to wash your hands when you come in from outside? Does she insist that they be rinsed when you're finished playing?

The priests serving in the Beit HaMikdash are commanded to wash their hands and feet (they worked barefoot) before taking part in the service.

This is an act of reverence and purification.

A large copper fountain stood in the courtyard, enabling them to fulfill this Mitzvah properly.

Today, we also serve HaShem in some ways that are comparable to the service in the Beit HaMikdash.

We, too, wash our hands (in a special way) in the morning, before eating, and in preparation for prayer.