This refers to those who continue to sin (verse 18) and then mockingly challenge God to stop them. Alternate translation: "those mockers who say" (See: [[rc://en/ta/man/translate/figs-irony]])
God's plans are spoken of as if they were objects that could come by themselves. Alternate translation: "let the Holy One of Israel accomplish his plans" (See: [[rc://en/ta/man/translate/figs-metaphor]])