כִּֽי־כֹה֙ אָמַ֣ר יְהוָ֔ה חִנָּ֖ם נִמְכַּרְתֶּ֑ם וְלֹ֥א בְכֶ֖סֶף תִּגָּאֵֽלוּ׃
For thus saith the LORD: Ye were sold for nought; And ye shall be redeemed without money.
Read kabbalistic (mystical) interpretation of Isaiah 52:3: and classical mystical sources.