Atharvaveda 4.32.7

4.32.7

abhí préhi dakṣiṇató bhavā nó 'dhā vr̥trā́ṇi jaṅghanāva bhū́ri |
juhómi te dharúṇaṃ mádhvo ágram ubhā́v upāṃśú prathamā́ pibāva ||7||

Go thou forth against [them]; be on our right hand; then will we (two) smite and slay many Vṛtras; I offer to thee the sustaining top of the sweet (mádhu); let us both drink first the initial draught (? upāṅçú).