नाऽधर्मश्चरितो लोके सद्यः फलति गौरिव ।
शनैरावर्तमानस्तु कर्तुर्मूलानि कृंतति ॥
The results of the deeds of cruelty (against dharma the code of life) are not immediately apparent unlike the benefits of domesticating a cow (you get milk on day one). Slowly the effects of mis-deeds surround the doer and cut the very roots of the source. Perpetrating cruelty will always end in the destruction of the culprit.
- Manu Smriti
Update: Thanks Gayathri for pointing out the typo.