Shatapatha Brahmana 11.4.2.8

11.4.2.8

atha haitadūrdhvam yo'yaṃ śanairādāyoccairnidadhāti sa yamicecreyāntsyāditi tasya śanairādāyoccairnidadhyāttena sa śreyānbhavati

And the ascending one, indeed, it is when he begins in a low tone and concludes in a high tone: whoever should wish that any one should be more prosperous, let him begin for him in a low tone and conclude in a high tone; and he will thereby become more prosperous.