Kauṣītaki Upaniṣad 2.2.1

2.2.1

prāṇo brahmeti ha smāha paiṅgyaḥ /

Prâna (breath) is Brahman, thus says Paiṅgya. And in that prâna, which is Brahman, the eye stands firm behind speech, the ear stands firm behind the eye, the mind stands firm behind the car, and the spirit stands firm behind the mind. To that prâna, which is Brahman, all these deities bring an offering, though he asks not for it, and thus to him who knows this, all creatures bring an offering, though he asks not for it. For him who knows this, there is this Upanishad (secret vow), 'Beg not!' As a man who has begged through a village and got nothing sits down and says, 'I shall never eat anything given by those people,' and as then those who formerly refused him press him (to accept their alms), thus is the rule for him who begs not, but the charitable will press him and say, 'Let us give to thee.'