In the Latter Day Saint movement, a hosanna shout is an organized ritual of a congregation of shouting hosanna. It was first performed as a ritual in the dedication of the Kirtland Temple, and was a part of the Kirtland endowment ceremony. It continues to be practiced by some Latter Day Saint denominations, most notably The Church of Jesus Christ of Latter-day Saints (LDS Church), which practices the ritual at the dedication of each of its temples.
The Encyclopedia of Mormonism states:
When the ordinance of the washing of feet was introduced at Kirtland, shouts of hosanna were viewed as a sealing benediction on both private and quorum prayer and then on the dedicatory prayer. At prayer meetings in the Kirtland Temple, the Saints sometimes used related phrases such as "Blessed is the name of the Most High God" and "Glory to God in the highest" (HC 2:386).
The Hosanna Shout is whole-souled, given to the full limit of one's strength. The congregation stands and in unison shouts the words "Hosanna, Hosanna, Hosanna to God and the Lamb. Amen, Amen, and Amen," repeating them three times. This is usually accompanied by the rhythmic waving of white handkerchiefs with uplifted hands. The epithet "Lamb" relates to the condescension and Atonement of Jesus Christ.