Kauṣītaki Upaniṣad 2.1.13

2.1.13

eṣa dharmo 'yācato bhavati /

Of him who knows this, the secret doctrine (_upaniṣad_) is: ‘One should not beg.’ It is as if, having begged of a village and not having received, one were to sit down, saying: ‘I would not eat anything given from here!’ and then those very ones who formerly refused him invite him, saying: ‘Let us give to you!’ Such is the virtue (_dharma_) of the non-beggar. Charitable people, however, address him, saying divinities without his begging bring offering. Likewise indeed, to him all beings without his begging bring offering.