Text 52] The Appearance of the Demon Vṛtrāsura
155
yad vā aśvaśiro nāma tayor amaratām vyadhāt
saḥ—he; vā—certainly; adhigataḥ—having obtained; dadhyaṅ—  Dadhyañca;  aśvibhyām—to the two Aśvini-kumāras; brahma—spiritual  knowledge;  niṣkalam—pure; yat vā—by which; aśvaśiraḥ—Aśvaśira:   nāma—named; tayoḥ—of the two; amaratām—liberation in one's life:   vyadhāt—awarded.
TRANSLATION
That saintly Dadhyañca, who is also known as Dadhici, personally assimilated the spiritual science and then delivered it to the Aśvini-kumāras. It is said that Dadhyañca gave them mantras through the head of a horse. Therefore the mantras are called Aśvaśira. After obtaining the mantras of spiritual science from Dadhici, the Aśvini-kumāras became jīvan-mukta, liberated even in this life.
PURPORT
The following story is narrated by many  ācāryas  in their commentaries:
niśamyātharvaṇam dakṣam pravargya-brahmavidyayoḥ. dadhyañcam   samupāgamya tam ūcatur athāśvinau. bhagavan dehi nau vidyām iti śrutvā sa cābravīt.   kamupāny avasthito 'dyāham paścād vakṣyāmi gacchatam. tayor nirgatayor eva śakra   āgatya tam munim. uvāca bhiṣajor vidyām mā vādīr aśvinor mune. yadi mad-vākyam   ullanghya bravīṣi sahasaiva te. śiraś-chindyām na sandeha ity uktvā sa yayau hariḥ.   indre gate tathābhyetya nāsatyāv ūcatur dvijam. tan-mukhād indra-gaditam śrutvā tāv   ūcatuḥ punaḥ. āvām tava śiraś chittvā pūrvam aśvasyā mastakam. sandhāyāvas tato   brūhi tena vidyām ca nau dvija. tasminn indreṇa sañchinne punaḥ sandhāyā   mastakam. nijam te dakṣiṇām dattvā gamiṣyāvo yathāgatam. etac chrutvā tadovāca   dadhyaṅṅ ātharvaṇas tayoḥ pravargyam brahma-vidyām ca sat-kṛto 'satya-śaṅkitaḥ.
The great saint Dadhici had perfect knowledge of how to perform fruitive activities, and he had advanced spiritual knowledge as well. Knowing this, the Aśvini-kumāras once approached him and begged him to instruct them in spiritual science ( brahma-vidyā ). Dadhici Muni replied, "I am now engaged in arranging sacrifices for fruitive activities. Come back some time later." When the Aśvini-kumāras left, Indra, the