Image: Prohibition era (1920 to 1933) image showing the disposal of alcohol.

From Doctrine and Covenants 89:2,3, the revelation giving the Word of Wisdom[footnote]Doctrine and Covenants 89[/footnote]

2 To be sent greeting; not by commandment or constraint, but by revelation and the word of wisdom, showing forth the order and will of God in the temporal salvation of all saints in the last days—

3 Given for a principle with promise, adapted to the capacity of the weak and the weakest of all saints, who are or can be called saints.

In 1921, in the midst of the United States prohibition ban on alcohol, church leaders made adherence to the Word of Wisdom a requirement for admission to the temple.[footnote]The Word of Wisdom: From Principle to Requirement – Dialog Journal[/footnote]

Crash Course:

The Word of Wisdom: From Principle to Requirement – Dialog Journal
Word of Wisdom – Wikipedia
Word of Wisdom – Mormon Think
Doctrine and Covenants 89