Shloka 18
उशनसः (शुक्रस्य) चरितम् — The Account of Uśanā (Śukra): Yoga, Grievance, and Pacification
क्षपयित्वा तु तं कालं गणितं कालचोदिता: । सावशेषेण कालेन सम्भवन्ति पुन: पुन:,इस प्रकार स्वर्ग अथवा नरकमें कर्मफलभोगद्दारा निश्चित समय व्यतीत करके भोगनेसे बचे हुए कर्म-सहित कालकी प्रेरणासे वे बारंबार इस संसारमें जन्म लेते रहते हैं
kṣapayitvā tu taṃ kālaṃ gaṇitaṃ kālacoditāḥ | sāvaśeṣeṇa kālena sambhavanti punaḥ punaḥ ||
Bhīṣma said: Having exhausted that fixed, reckoned span of time—impelled by Time itself—they are born again and again, as long as some residue of their karma still remains to be experienced. Thus, even after enjoying the fruits of deeds in heaven or hell for the allotted period, beings return to worldly existence until the remaining karmic balance is worked out.
भीष्म उवाच
Educational Q&A
Even after a being enjoys or suffers the results of actions in heaven or hell for a fixed duration, rebirth continues until the remaining (residual) karma is exhausted; Time (kāla) is presented as the force that propels this recurring cycle.
In Bhīṣma’s instruction to Yudhiṣṭhira in the Śānti Parva, he explains the mechanics of post-mortem experience and return: beings spend the allotted term for their karmic fruits, and then—if any karmic residue remains—Time drives them back into repeated births in the world.