وَتَزْجُرُ عَنِ الظُّلْمِ ثُمَّ تَغْشَاهُ
You sharply forbid injustice, then go on to commit it yourself.
Tazjuru means to rebuke or restrain firmly. Taghshāhu literally conveys approaching or entering something, here falling into injustice.
Thumma places the second act after the first: public denunciation followed by private violation. Sequence intensifies the rebuke.