Rashi on Exodus 30:20/רש"י על שמות ל׳:כ׳

1בבאם אל אהל מועד WHEN THEY COME INTO THE APPOINTED TENT to burn incense in the morning and at evening, or to sprinkle of the blood of the bullock offered by the anointed High-Priest (Leviticus 4:5, 7) and of the he-goats offered as atonement for the sin of idolatry (all of which services were performed in the interior of the Sanctuary) (Zevachim 19b).

2ולא ימתו THAT THEY DIE NOT — thus it follows that if they do not wash they will die: You may rightly draw this conclusion for in the Torah laws are sometimes stated only by implication: consequently from what is said here in the negative (that they die not) you may derive the positive (that they will die if they do not observe the law here laid down).

3אל המזבח [OR WHEN THEY STEP] NEAR THE ALTAR — i. e. the outer altar, in which case there is no entering into the appointed tent but the service is performed in the court.