Joshua 4:18-21
English Standard Version
19The people came up out of the Jordan on the tenth day of the first month, and they encamped at Gilgal on the east border of Jericho.
20And those twelve stones, which they took out of the Jordan, Joshua set up at Gilgal.
21And he said to the people of Israel, "When your children ask their fathers in times to come, ‘What do these stones mean?’