Joshua 3:1-3

And Joshua rose up early in the morning; and they removed from Shittim, and came to the Jordan, he and all the children of Israel; and they lodged there before they passed over. And it came to pass after three days, that the officers went through the midst of the camp; and they commanded the people, saying, When ye see the ark of the covenant of Jehovah your God, and the priests the Levites bearing it, then ye shall remove from your place, and go after it.