Courtesy of Ohr Somayach! Check out their Rosh Hashana site at http://www.ohr.org.il/special/roshhash/!

Question: On one historic Yom Kippur, the entire Jewish people ate and drank and were praised for it by Hashem; when did this occur?

See Answer

Answer: When King Solomon built the Temple, Yom Kippur occurred during its seven Inauguration Days. The Sanhedrin decided that not only must the Inauguration Sacrifices for the Temple be offered but, moreover, the people must cook, eat, and drink on Yom Kippur or else the happiness of the Inauguration would be incomplete. (See Tractate Mo'ed Katan 9a.)

Courtesy of Ohr Somayach! Check out their Rosh Hashana site at http://www.ohr.org.il/special/roshhash/!