Here’s a passage from page 517 of Harry Potter and the Deathly Hallows:

(Ron’s brother Bill is warning Harry against trusting a goblin Griphook.)

“You don’t understand, Harry, nobody could understand unless they have lived with goblins. To a goblin, the rightful and true master of any object is the maker, not the purchaser. All goblin-made objects are, in goblin eyes, rightfully theirs.”

“But if it was bought – ”

“- then they would consider it rented by the one who had paid the money. They have, however, great difficulty with the idea of goblin-made objects passing from wizard to wizard. […] They consider our habit of keeping goblin-made objects, passing them from wizard to wizard without further payment, little more than theft.”