Unlike the other Keilim, the Kiyor was not used in the Avodah. It was used as a preparation for the Avodah and was the first Keli to be used each day. If a Kohen did not wash their hands and feet before the Avodah, their service would be invalid.
The Beis Hamikdash comprises 3 main areas; the Azarah (courtyard), the Kodesh and the Kodesh Hakodashim. These areas and the Avodah performed within them, represent 3 phases in lifting ourselves up to connect to Hashem.
The first step when leaving the street to enter the “Beis Hamikdash” of spiritual growth, is the Azarah. The Azarah, like a courtyard, is a preparation before entering into Kodesh and ultimately the Kodesh Hakodoshim. The Kiyor stood in the Azarah.
Before entering our homes, we wipe our feet at the door so that we don’t dirty the floor with mud that has been brought in from the street. Without a doormat, the most beautiful home will quickly become spoiled.
When a person leaves the outside world and seeks spiritual growth, the first thing that they need to do is to wash off any ‘dirt’ from the outside which may have stuck onto them. These include worldly attitudes and influences which are contrary to Kedusha. If not removed, they will hold us back from real spiritual growth.
Then we can engage in our Avodah with the Keilim of Torah and Tefillah, climbing the rungs of holiness in absolute purity.
Based on Reshimas Hamenora written by the Lubavitcher Rebbe