Forefathers (SB cantos 5 - 12)
Srimad-Bhagavatam
SB Canto 5
The King became pitṛloka-kāma, or desirous of being transferred to the planet named Pitṛloka. Pitṛloka is mentioned in Bhagavad-gītā (yānti deva-vratā devān pitṟn yānti pitṛ-vratāḥ (BG 9.25)). To go to this planet, one needs very good sons who can make offerings to Lord Viṣṇu and then offer the remnants to their forefathers. The purpose of the śrāddha ceremony is to please the Supreme Personality of Godhead, Lord Viṣṇu, so that after pleasing Him one may offer prasāda to one's forefathers and in this way make them happy. The inhabitants of Pitṛloka are generally men of the karma-kāṇḍīya, or fruitive activities category, who have been transferred there because of their pious activities. They can stay there as long as their descendants offer them viṣṇu-prasāda. Everyone in heavenly planets such as Pitṛloka, however, must return to earth after exhausting the effects of his pious acts. As confirmed in Bhagavad-gītā (9.21), kṣīṇe puṇye martya-lokaṁ viśanti: persons who perform pious acts are transferred to higher planets, but when the effects of their pious acts are over, they are again transferred to earth.