1. The Priests, cf. Leviticus 10:8-11: And the LORD spake unto Aaron, saying, Do not drink wine nor strong drink, thou, nor thy sons with thee, when ye go into the tabernacle of the congregation, lest ye die: it shall be a statute for ever throughout your generations: And that ye may put difference between holy and unholy, and between unclean and clean; And that ye may teach the children of Israel all the statutes which the LORD hath spoken unto them by the hand of Moses.
This command to abstain comes after the record of the folly of Nadab and Abihu, who offered strange fire to the Lord, and who were consumed, cf. Leviticus 10:1-7. Was it imbibing alcohol that made them engage in such folly? Is this why the prohibition was given to Aaron and his sons immediately afterwards? It would seem so!
2. The King and the Prince, cf. Proverbs 31:4,5: It is not for kings, O Lemuel, it is not for kings to drink wine; nor for princes strong drink: Lest they drink, and forget the law, and pervert the judgment of any of the afflicted. Wine and strong drink would have a harmful effect upon the king in the exercise of his royal authority.