The Old Testament Priesthood

In 1 Samuel 21, a hemlock offers David and his men holy bread. Only the priests are allowed to eat it; this provision that allows people to work on the Sabbath is specifically only given for priests. So what's implied in this is that the apostles have a priestly role. In other words, consecrated set aside. Then there was holy warfare or a special mission. Israelite soldiers would abstain from all sexual relations while they're on military service.