When the priest was on duty he was to abstain from wine and strong drink, lest he should commit excess (see Leviticus 10:1), and so become disqualified for carrying out the precepts of the ceremonial Law.
Strong drink - The Hebrew word is employed here to denote strong drinks of any kind except wine made from the grape.
Unholy ... unclean - Common, as not consecrated; and what would occasion defilement by being touched or eaten. Compare Acts 10:14.
That is, “that you may, by your example in your ministrations, preserve the minds of the Israelites from confusion in regard to the distinctions made by the divine Law.”