בְּזֹ֖את תִּבָּחֵ֑נוּ חֵ֤י פַרְעֹה֙ אִם־תֵּצְא֣וּ מִזֶּ֔ה כִּ֧י אִם־בְּב֛וֹא אֲחִיכֶ֥ם הַקָּטֹ֖ן הֵֽנָּה׃
Hereby ye shall be proved, as Pharaoh liveth, ye shall not go forth hence, except your youngest brother come hither.
Read kabbalistic (mystical) interpretation of Genesis 42:15: and classical mystical sources.