Leviticus 23:23—24, “The LORD also said to Moses, “Speak to the Israelites and say, ‘On the first day of the seventh month you are to have a day of rest, a sacred assembly announced by trumpet blasts.” What makes this feast different is that is happens on a day when no one knew exactly what day it will be. The first day of the new month during the time of Moses needed to be verified by at least two witnesses who observed the new moon. They needed to be carefully watching the waning moon to be able to identify the first sliver of the new moon.