Śatapatha Brāhmaṇa ("of a hundred paths") 5.3.4.23

5.3.4.23

ṣoḍaśa tā āpo yā abhijuhoti | ṣoḍaśāhutīrjuhoti tā dvātriṃśaddvayīṣu na juhoti sārasvatīṣu ca marīciṣu ca tāścatustriṃśattrayastriṃśadvai devāḥ prajāpatiścatustriṃśastadenam prajāpatiṃ karoti

Now sixteen kinds of water are those he offers upon; and he offers sixteen oblations: that makes thirty-two. On two of them he does not offer, viz. on the water from the Sarasvatî and on the sun-motes: that makes thirty-four. For three and thirty are the gods, and Pragâpati is the thirty-fourth: he thus makes him to be Pragâpati (the lord of creatures).