An apostate once led the king into a synagogue at precisely the hour when the Torah reader was chanting the verse from Deuteronomy: "How can one pursue a thousand, and two put ten thousand to flight?" (Deuteronomy 32:30).
The apostate whispered to the king, "Did you hear that? The Jews are boasting that a single Jew can kill ten thousand men."
The king, enraged, called the teacher of the synagogue to explain. The teacher answered carefully: "The verse refers to the generation who came out of Egypt with Moses, who were great in merit. In our own day we could not do such a thing."
The king did not accept this. He summoned the whole council of elders. "You are their descendants," he said. "Prove it. I give you one year. If you cannot demonstrate that one of you can scatter ten thousand, you will all be driven out of my kingdom, or killed."
The Jews decreed a fast of six months. They wept. Then a traveler came forward and said, "I will cross the river Sambatyon and reach the Children of Moses who live beyond it. They keep the old holiness intact. One of them will be able to fulfill the prophecy."
The Sambatyon is a legendary river that, in Jewish tradition, rushes with stones all week long and only stops on Shabbat — when no Jew may cross. The traveler gave money for the journey and set out. He traveled five months and reached the river — and crossed, because the river was calm that day, being the Sabbath.
The Children of Moses, finding him on their side on Shabbat, condemned him to death for having broken the Sabbath to cross. He begged leave to show them his letter. They read it. They understood the urgency. They relented, and sent with him a young girl of their own — a child of the hidden tribes.
She and the traveler returned by a miraculous shortening of the road, one day's journey home. They arrived in the capital in time.
The king gathered all his armies in a great field. The girl from beyond Sambatyon, dressed in the plain robe of her people, came out to face them. She asked the king to have two huge millstones cut from a nearby mountain. They were made — stones weighing six hundred tons apiece. Then she lifted her face to heaven and pronounced the Ineffable Name of God. The two millstones rose into the air, turning slowly, and descended upon the army.
Every soldier was ground to dust between the two stones.
The king, seeing it, fell on his face. "If this can be done by a single word from her mouth," he said, "what strength must your God have in His own hand?" He acknowledged the truth of Torah before the whole court. The Jews rejoiced. The girl, her task complete, returned to her people beyond the river.
The Exempla preserves this wild tale as an exile's dream of rescue — a legend that Moses' own original tribes were still faithful somewhere, and that at the last moment of crisis, the old holiness could reach across even the stones of Sambatyon to save what was left.
(From The Exempla of the Rabbis, Moses Gaster, 1924, no. 445.)