ŚBM, 13, 3, 3, 10.0 śiro vā etadyajñasya yadekaviṃśaḥ yo vā aśvamedhe trīṇi śīrṣāṇi veda śiro ha rājñām bhavaty ekaviṃśo 'gnirbhavaty ekaviṃśa stoma ekaviṃśatiryūpā etāni vā aśvamedhe trīṇi śīrṣāṇi tāni ya evaṃ veda śiro ha rājñām bhavati yo vā aśvamedhe tisraḥ kakudo veda kakuddha rājñām bhavaty ekaviṃśo'gnirbhavaty ekaviṃśa stoma ekaviṃśatiryūpā etā aśvamedhe tisraḥ kakudas tā ya evaṃ veda kakuddha rājñām bhavati //