(Sermon starts at 22:00 in the recording).
14 So it was, when the people set out from their camp to cross over the Jordan, with the priests bearing the ark of the covenant before the people, 15 and as those who bore the ark came to the Jordan, and the feet of the priests who bore the ark dipped in the edge of the water (for the Jordan overflows all its banks during the whole time of harvest), 16 that the waters which came down from upstream stood still, and rose in a heap very far away at Adam, the city that is beside Zaretan. So the waters that went down into the Sea of the Arabah, the Salt Sea, failed, and were cut off; and the people crossed over opposite Jericho. 17 Then the priests who bore the ark of the covenant of the Lord stood firm on dry ground in the midst of the Jordan; and all Israel crossed over on dry ground, until all the people had crossed completely over the Jordan.
4 And it came to pass, when all the people had completely crossed over the Jordan, that the Lord spoke to Joshua, saying: 2 “Take for yourselves twelve men from the people, one man from every tribe, 3 and command them, saying, ‘Take for yourselves twelve stones from here, out of the midst of the Jordan, from the place where the priests’ feet stood firm. You shall carry them over with you and leave them in the lodging place where you lodge tonight.’ ”
4 Then Joshua called the twelve men whom he had appointed from the children of Israel, one man from every tribe; 5 and Joshua said to them: “Cross over before the ark of the Lord your God into the midst of the Jordan, and each one of you take up a stone on his shoulder, according to the number of the tribes of the children of Israel, 6 that this may be a sign among you when your children ask in time to come, saying, ‘What do these stones mean to you?’ 7 Then you shall answer them that the waters of the Jordan were cut off before the ark of the covenant of the Lord; when it crossed over the Jordan, the waters of the Jordan were cut off. And these stones shall be for a memorial to the children of Israel forever.”
Joshua 3:14-4:7 (NKJV)