Joshua 3:14-4:7

So, when the people set out from their tents, to pass over the Jordan with the priests bearing the ark of the covenant before the people, and when those who bore the ark had come to the Jordan, and the feet of the priests bearing the ark were dipped in the brink of the water (the Jordan overflows all its banks throughout the time of harvest), the waters coming down from above stood and rose up in a heap far off, at Adam, the city that is beside Zar'ethan, and those flowing down toward the sea of the Arabah, the Salt Sea, were wholly cut off; and the people passed over opposite Jericho. And while all Israel were passing over on dry ground, the priests who bore the ark of the covenant of the LORD stood on dry ground in the midst of the Jordan, until all the nation finished passing over the Jordan. When all the nation had finished passing over the Jordan, the LORD said to Joshua, "Take twelve men from the people, from each tribe a man, and command them, `Take twelve stones from here out of the midst of the Jordan, from the very place where the priests' feet stood, and carry them over with you, and lay them down in the place where you lodge tonight.'" Then Joshua called the twelve men from the people of Israel, whom he had appointed, a man from each tribe; and Joshua said to them, "Pass on before the ark of the LORD your God into the midst of the Jordan, and take up each of you a stone upon his shoulder, according to the number of the tribes of the people of Israel, that this may be a sign among you, when your children ask in time to come, `What do those stones mean to you?' Then you shall tell them that the waters of the Jordan were cut off before the ark of the covenant of the LORD; when it passed over the Jordan, the waters of the Jordan were cut off. So these stones shall be to the people of Israel a memorial for ever."