וְעַתָּה֙ לְכ֣וּ עִבְד֔וּ וְתֶ֖בֶן לֹא־יִנָּתֵ֣ן לָכֶ֑ם וְתֹ֥כֶן לְבֵנִ֖ים תִּתֵּֽנּוּ׃
Go therefore now, and work; for there shall no straw be given you, yet shall ye deliver the tale of bricks.’
Read kabbalistic (mystical) interpretation of Exodus 5:18: and classical mystical sources.