Why sinful acts do not bear fruit immediately in many cases?

 

According to Hinduism, Karma, whether good or bad, works in its own way. It may not fructify immediately, many a time, but fructify at a later date.

Mahabharata contains the following saying, stated by Sage Shukracharya to the King Vṛṣaparva.

ततः काव्यो भृगुश्रेष्ठः समन्युरुपगम्य ह
वृषपर्वाणमासीनमित्युवाचाविचारयन्

tataḥ kāvyo bhṛguśreṣṭhaḥ samanyur upagamya ha
vṛṣaparvāṇam āsīnam ity uvācāvicārayan

Then Kavya (Shukracharya), the foremost of Bhrigu's line, became angry himself. And approaching Vrishaparvan where the latter was seated, began to address him without weighing his words.

नाधर्मश्चरितो राजन्सद्यः फलति गौरिव
पुत्रेषु वा नप्तृषु वा न चेदात्मनि पश्यति
फलत्येव ध्रुवं पापं गुरुभुक्तमिवोदरे

nādharmaś carito rājan sadyaḥ phalati gaur iva
putreṣu vā naptṛṣu vā na ced ātmani paśyati
phalaty eva dhruvaṃ pāpaṃ guru bhuktam ivodare

'O king,' he said, 'sinful acts do not, like the Cow, bear fruit immediately! But gradually and secretly do they extirpate their doers. Such fruit visit either in one's own self, one's son, or one's grandson. Sins must bear their fruit. Like rich food they can never be digested.