وَأَنَّ عَذَابِى هُوَ ٱلْعَذَابُ ٱلْأَلِيمُ
Saheeh International(50) And that it is My punishment which is the painful punishment.
English Translation - Rowwad Translation Centerand that My punishment is the most painful punishment.
English Translation - Hilali and Khan50. And that My Torment is indeed the most painful torment.