Translation:

21. Yea how (terrible) was my Penalty and my Warning!

Notes (Tafseer)

5145. Repeated from verse 18 to heighten the description of the sin, the penalty, and the criminal negligence of the sinners in refusing the warnings on account of their self- complacent confidence in their own strength and stability! It is repeated again as a secondary refrain in liv. 30 and (with slight modification) in liv. 32 and 39.