Translation:

18. "And swell not thy cheek (for pride) at men nor walk in insolence through the earth; for Allah loveth not any arrogant boaster.

Notes (Tafseer)

3603. The word "cheek" in English, too, means arrogance or effrontery, with a slightly different shade added, viz.: effrontery from one in an inferior position to one in a superior position. The Arabic usage is wider, and includes smug self-satisfaction and a sense of lofty Superiority.