'Priest's' in the Bible

And it came to pass, that while he executed the priest's office before God in the order of his course,

According to the custom of the priest's office, his lot was to burn incense when he went into the temple of the Lord.

Then one of them struck the high priest’s slave and cut off his right ear.

Then took they him, and led him, and brought him into the high priest's house. And Peter followed afar off.