Śatapatha Brāhmaṇa ("of a hundred paths") 4.3.5.13

4.3.5.13

atha dadhi gṛhṇāti | ādityānāṃ vai tṛtīyasavanamādityānvā anu paśavastatpaśuṣvevaitatpayo dadhāti tadidam paśuṣu payo hitam madhyata iva gṛhṇīyādityāhurmadhyata iva hīdam paśūnām paya iti paścādiva tveva gṛhṇīyātpaścādiva hīdam paśūnām payaḥ

Thereupon he takes sour milk; for the evening pressing belongs to the Âdityas, and cattle are after (the manner of) the Âdityas: he thereby puts milk into the cattle, and thus that milk in cattle is beneficial. 'He should put it right in the centre (of the Âditya cup),' they say, 'for that milk is right in the centre of cattle.' But let him rather put it in the back part (of the cup), for that milk is in the hind part of cattle.