Rashi on Exodus 22:22/רש"י על שמות כ״ב:כ״ב

1אם ענה תענה אתו IF THOU AFFLICT THEM IN ANY WISE — This is an elliptical phrase — the text threatens but breaks off and does not specify immediately the punishment which will fall upon those who do this. We have the same in, (Genesis 4:15) “Therefore whosoever slayeth Cain …” it threatens but does not specify the punishment. So, here, too: “If thou afflict them in any wise”, — this is a threat, as much as to say: “in the end you will get your deserts!” Why are you certain to get them? “Because (כי) if (אם) they cry at all unto Me, I will surely hear their cry”.