On learning his resolve, the sons of Diti and the Danavas, who live in the nether region and who were once defeated by the celestials, fearing that their party would be destroyed without Duryodhana, began a sacrifice with fire to summon him before them. Mantraknowing men then commenced with the formulae of Brihaspati and Ushana. Those rites that are indicated in the Atharvaveda and the Upanishadas and which are capable of being achieved by mantras and prayers.