The Mahabharata of Krishna-Dwaipayana Vyasa…
“ That ritual is auspicious, worthy of praise, productive of fame and progeny, and is regarded as a sacrifice, O scorcher of foes, in honour of the Pitris. Gods or Asuras or human beings, Gandharvas or Uragas or Rakshasas, Pisachas or Kinnaras,—every one should always worship the Pitris. It is seen that people worship the Pitris first, and gratify the deities next by offering them their adorations. Hence, one should always worship the Pitris with every care. ”
