What did the constitution say about the president buying land?

The US Constitution made no provision for purchasing territory nor for conferring US citizenship on the people in that territory. The Louisiana Purchase was the first test. Jefferson, while a strict constructionist of the Constitution, realized the importance of the purchase. He is quoted as saying, ". . . what is practicable must often control what is pure theory." And, he instructed his followers in Congress that "the less we say about constitutional difficulties. . .the better."