How did Hugo Grotius connect lying with moral wrongness?

Hugo Grotius connected lying with moral wrongness by arguing that the concept of moral wrongness is inherently built into the very definition of a lie.1

For Grotius, this relationship is tautological: because he defined a lie as something that is inherently immoral, a "harmless falsehood" does not qualify as a lie by definition. Therefore, in his view, asserting that lying is immoral is simply a statement of the term's own nature.1