וַיִּרְא֞וּ שֹֽׁטְרֵ֧י בְנֵֽי־יִשְׂרָאֵ֛ל אֹתָ֖ם בְּרָ֣ע לֵאמֹ֑ר לֹא־תִגְרְע֥וּ מִלִּבְנֵיכֶ֖ם דְּבַר־י֥וֹם בְּיוֹמֽוֹ׃
And the officers of the children of Israel did see that they were set on mischief, when they said: ‘Ye shall not diminish aught from your bricks, your daily task.’
Read kabbalistic (mystical) interpretation of Exodus 5:19: and classical mystical sources.