Garudapurana 2.48.7

2.48.7

yaḥ kṣattriyo bāhubalena saṃyuge lalāṭadeśādrudhiraṃ mukhe papau /
tatsomapānaṃ hi kṛtaṃ mahāmakhe jīvanmṛtaḥ so 'pi hi yāti muktik //

The kṣatriya who, by the strength of his arms in battle, drank blood from the forehead region onto his face— / indeed, that was the drinking of soma performed in a great sacrifice; even while living he is dead, and he goes to liberation.