Rashi on Leviticus 10:10/רש"י על ויקרא י׳:י׳

1ולהבדיל AND TO DISTINGUISH [BETWEEN THE HOLY AND THE UNHOLY] — i. e., Observe this law in order that ye may be able to distinguish between a holy (valid) sacrificial act and one which has become profane (invalid). Thus you may learn that if one performed a sacrificial rite in a state of intoxication his ministry was invalid (Sifra, Shemini, Section 1 8; Zevachim 17b).