Ashvamedha Yajna
अश्वमेध यज्ञ
Also known as वाजिमेधः
The Ashvamedha is the most important and elaborate of the Vedic shrauta sacrifices: a horse is released to wander freely for a year, and the kingdoms it enters must either submit or fight, after which the sacrifice is duly completed. It served both as the mark of universal sovereignty and as an expiation. At SB 1.12.34 Yudhishthira performs three of them to expiate the killing of his kinsmen — though at SB 1.8.52 he had himself said that the slaughter of beings cannot be washed away by sacrifices; hence the purification is finally through worship of Hari ('samayajad dharim').
Śrīmad Bhāgavata Mahāpurāṇa 1.12.34 — Sanskrit Wikisource (pinned oldid=110183)