Manava Dharmashastra 5.86

5.86

naro manuṣyastasyedaṃ nāram | sasnehaṃ māṃsamajjādigdham | gorālambhanaṃ sparśaḥ | arkadarśanagavālambhau vikalpyete |

Having touched a fatty human bone, the Brāhmaṇa becomes pure by bathing, but if it be free from fat, then by sipping water and touching a cow, or looking at the sun—(86).

Medhātithi’s commentary (manubhāṣya):
‘Nāra,’ ‘human,’—belonging to man.

‘Fatty’—i.e. Besmeared with flesh, marrow &c.

‘Ālabhya’ means touching.

The touching of the cow and looking at the sun are meant to be optional alternatives.—(86).