«وَلَمْ أُخْسِرْهُ وَشَرُّ الْوَرَى / مَنْ يَوْمُهُ أَخْسَرُ مِنْ أَمْسِهِ»
I did not shortchange him; the worst of people is one whose today is worse than yesterday.
Ukhsirhu concerns causing another a loss or deficiency; akhsar is a comparative meaning “more at a loss.” Related forms of the same root create distinct nuances.
The first half qualifies the earlier reciprocity: the speaker denies initiating dishonesty. The second half broadens the focus by comparing a person's moral condition today with that of yesterday.