The United States Constitution clearly delegates the power of the purse to Congress right up front in Article. 1, Section. 1:
All legislative Powers herein granted shall be vested in a Congress of the United States, which shall consist of a Senate and House of Representatives.
The composition, requirements and duties of each house of Congress are specified by the Founders in exquisite detail throughout Article 1. It comes first in the Constitution because Congress is closest to The People. At least, it was until the last century.
The Founders took such pains with the text because they knew the tendency for corruption, evil, and illegal power grabs inherent in human nature. It was as though they could see the spectre of a destructive and dictatorial Joe Biden lurking in the mists of a dark American future. In Section 9, clause 7, Article 1 definitively states:
No Money shall be drawn from the Treasury, but in Consequence of Appropriations made by Law; and a regular Statement and Account of the Receipts and Expenditures of all public Money shall be published from time to time.