Corollary 1
Tag 0AB1, permanent. Cite it as [Bourbaki, Tag 0AB1].
Lie Groups and Lie Algebras, chapter III, § 3. Passage from a Lie group to its Lie algebra
In the notation of Proposition 39, the set of such that is a Lie subgroup of and its Lie algebra is the set of such that maps into .
We apply Proposition 39 with .
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.