וְנָתַתִּ֛י אֶת־חֵ֥ן הָֽעָם־הַזֶּ֖ה בְּעֵינֵ֣י מִצְרָ֑יִם וְהָיָה֙ כִּ֣י תֵֽלֵכ֔וּן לֹ֥א תֵלְכ֖וּ רֵיקָֽם׃
And I will give this people favour in the sight of the Egyptians. And it shall come to pass, that, when ye go, ye shall not go empty;
Read kabbalistic (mystical) interpretation of Exodus 3:21: and classical mystical sources.