Śatapatha Brāhmaṇa ("of a hundred paths") 3.3.2.14

3.3.2.14

etayā sarvābhiḥ | etayā catasṛbhiretayā tisṛbhiretayā dvābhyāmetayaikayaitayaivaikayaitayā tisṛbhiretayā catasṛbhiretayā sarvābhiḥ samasyāñjalinādhyāvapati

He metes out while bending up and bending down (the fingers). The reason why he metes out in bending (the fingers) up and down is that he thereby makes those fingers of separate existence, and therefore they are born separate (from each other); and as to his meting out with all (fingers) together, these (fingers) are to be born, as it were, united. This is why he metes out in bending (the fingers) up and down.