Śatapatha Brāhmaṇa ("of a hundred paths") 3.8.3.30

3.8.3.30

antareṇārdharcau yājyāyai vasāhomaṃ juhoti | ito vā ayamūrdhvo medha utthito yamasyā imaṃ rasam prajā upajīvantyarvācīnaṃ divo raso vai vasāhomo raso medho rasenaivaitadrasaṃ tīvrīkaroti tasmādayaṃ raso 'dyamāno na kṣīyate

In the interval between the two half-verses of the offering-prayer he offers the oblation of gravy. It is from out of this that that essence (juice) has risen upwards here,--that sap of this earth whereby creatures exist on this side of the sky; for the oblation of gravy is sap, and essence is sap: thus he renders the sap strong by means of sap, whence this sap when eaten does not perish.