וְאֶת־אֲחִיכֶ֤ם הַקָּטֹן֙ תָּבִ֣יאוּ אֵלַ֔י וְיֵאָמְנ֥וּ דִבְרֵיכֶ֖ם וְלֹ֣א תָמ֑וּתוּ וַיַּעֲשׂוּ־כֵֽן׃
and bring your youngest brother unto me; so shall your words be verified, and ye shall not die.’ And they did so.
Read kabbalistic (mystical) interpretation of Genesis 42:20: and classical mystical sources.