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:
kṣapayitvā tu taṃ kālaṃ gaṇitaṃ kālacoditāḥ | sāvaśeṣeṇa kālena sambhavanti punaḥ punaḥ ||
毗湿摩说道：当那被定下并计量的时限耗尽之后——为时间本身所驱使——只要尚有余业未受，众生便一再出生。是故，即便在天界或地狱于所分配的期限内受用业果，众生仍将回归世间，直至剩余的业债尽数消尽。
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.