Devibhagavatapurana 1.5.96

1.5.96

devyuvāca |
kiṃ te'bhīṣṭaṃ varaṃ brūhi vāñchitaṃ yaddadāmi tat |
parituṣṭāsmi bhaktyā te tapasā cādbhutena ca ||

The Devî said:-- “O child! I am very much satisfied with your wonderful tapasya and devotion. Now say what boon do you want. I will give you the boon that you desire”. Hayagrîva said;-- “O Mother! grant me that boon by which death will not come to me, and I be invincible by the Suras and Asuras, I may be a Yogi and immortal”.
The Devî said:-- “ Death brings in birth and birth brings in death; this is inevitable.” This order of things is extant in this world; never its violation takes place. O best of the Râksasas! Thus knowing death sure, think in your mind and ask another boon.
Hayagrîva said: -- “O Mother of the universe! If it be that Thou art not willing at all to grant me immortality, then grant me this boon that my death may not occur from any other than from one who is horse-faced. Be merciful and grant me this boon that I desire.”