Shatapatha Brahmana 11.1.5.3

11.1.5.3

śaśaścāndramasa iti candramā vai somo devānāmannaṃ tam paurṇamāsyāmabhiṣuṇvanti so'parapakṣe'pa oṣadhīḥ praviśati paśavo vā apa oṣadhīradanti tadenametāṃ rātrīm paśubhyaḥ saṃnayati

'The hare in the moon.' Soma, the food of the gods, indeed, is the moon: at full moon they press him; and in the subsequent half of the month he enters the waters and plants; and, the cattle feeding on the water and the plants, he then during that night (of new moon) collects him from the cattle.