4,008. Immersion vs. Sanctification

Hilchos Bias HaMikdash 5:5

One who relieves his bowel must immerse in a mikvah, while one who voids his bladder must sanctify his hands and feet. Regarding one who went outside the walls of the courtyard, if he left intending to remain outside for some time, he must immerse; if he intended to return immediately, he need only sanctify his hands and feet upon his return. If he served without immersing or sanctifying his hands and feet, the service is valid because he didn’t let his attention stray or empty his bowel or bladder. If he only stuck his hands outside the courtyard, he need not sanctify them again.

Hilchos Bias HaMikdash 5:6

If only a kohein’s hands were rendered ritually unclean, he may immerse them in order to purify them; they need not be sanctified again. Let’s say that his body was rendered unclean because he ate ritually unclean food or drank ritually unclean liquid and he immersed in a mikvah. Even though he need not wait until nightfall to be purified, he must still sanctify his hands and feet after his immersion. This is because anyone who immersed must sanctify his hands and feet before he can serve. If he neglected to sanctify his hands and feet, his service is not profaned because he didn’t let his attention stray.