Miscellanies 4.25.158

Only those who live purely, then, are truly priests of God. That is why, though all the tribes were circumcised, those anointing high priests, kings, and prophets were counted holier. For this reason he commands them not to touch the dead nor to go in to the departed; not as though the body were polluted, but because sin and disobedience are fleshly, bodily, dead, and therefore abominable. Only to father and mother, son and daughter, when they have died, is the priest allowed to go in, because these alone are kin of flesh and seed, from whom the priest has received the immediate cause of his entry into life. And these are purified for seven days, the days through which creation is completed; for on the seventh the rest is celebrated, and on the eighth he brings a propitiation, as is written in Ezekiel, according to which propitiation one may receive the promise.