1)
What is the significance of saying "like he did to me, so I will do to him"?
1.
R. Yonah: Even if your colleague transgressed Musar, and publicized your sins, do not do so to him. 'Due to one lunatic who did improperly, we should not lose our integrity!' (Avodah Zarah 55a)
2.
Malbim: Even if you [testify falsely about him] because he regularly hires himself to be a false witness, and you say 'I will return to him like his deed', do not do so in any case.
