Original: The Oath was a pledge signed by 576 out of the 577 members from the Third Estate and a few members of the First Estate during a meeting of the Estates-General of 20 June 1789 in a tennis court building near the Palace of Versailles.
Simplified: The oath was a pledge signed by 576 members out of 577 of France's Third Estate and a few members of the Second Estate on June 20, 1789 in a tennis court near the Palace of Versailles.