The Washing

The washing of the High Priest (& priests) was symbolic of the cleansing that we need to go through-for we cannot cleanse ourselves....

 

Take Aaron and his sons with him, and the garments, and the anointing oil, and a bullock for the sin offering, and two rams, and a basket of unleavened bread; And gather thou all the congregation together unto the door of the tabernacle of the congregation. And Moses brought Aaron and his sons, and washed them with water.

Leviticus 8:1,2,6

Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost;

Titus 3:5

Baptisim of our High Priest

Baptism of the "Priests"
But ye are a chosen generation,
 a royal priesthood,
an holy nation,
a peculiar people;
 that ye should shew forth the praises of him who hath called you out of darkness into his marvellous light:
1 Peter 2:9