Srimad-Bhagavatam: Canto 7 - Chapter 1 - Verse 22

Sanskrit:

कुरु त्वं प्रेतकृत्यानि पितु: पूतस्य सर्वश: ।मदङ्गस्पर्शनेनाङ्ग लोकान्यास्यति सुप्रजा: ॥ २२ ॥

ITRANS:

kuru tvaṁ preta-kṛtyānipituḥ pūtasya sarvaśaḥmad-aṅga-sparśanenāṅgalokān yāsyati suprajāḥ

Translation:

My dear child, your father has already been purified just by the touch of My body at the time of his death. Nonetheless, the duty of a son is to perform the śrāddha ritualistic ceremony after his father’s death so that his father may be promoted to a planetary system where he may become a good citizen and devotee.

Purport:

In this regard, Śrīla Viśvanātha Cakravartī Ṭhākura says that although Hiraṇyakaśipu was already purified, he had to take birth on a higher planetary system to become a devotee again. Prahlāda Mahārāja was advised to perform the ritualistic ceremony as a matter of etiquette, for the Supreme Personality of Godhead under no circumstances wants to stop the regulative principles. Madhva Muni also instructs: When the demons Madhu and Kaiṭabha were killed by the Supreme Personality of Godhead, their kinsmen also observed the ritualistic ceremonies so that these demons could return home, back to Godhead.