II. Respect for Persons and Their Goods

From The Catechism of the Catholic Church

2413
Games
of chance (card games, etc.) or wagers are not in themselves contrary to justice.
They become morally unacceptable when they deprive someone of what is necessary
to provide for his needs and those of others. the passion for gambling risks
becoming an enslavement. Unfair wagers and cheating at games constitute grave
matter, unless the damage inflicted is so slight that the one who suffers it
cannot reasonably consider it significant.

PART THREE: LIFE IN CHRIST

SECTION TWO THE TEN COMMANDMENTS
- CHAPTER TWO YOU SHALL LOVE YOUR NEIGHBOR AS YOURSELF
  - Article 7 THE SEVENTH COMMANDMENT
    - II. Respect for Persons and Their Goods

From The Catechism of the Catholic Church – rosary.team