Proposition 7
Tag 0AIT, permanent. Cite it as [Bourbaki, Tag 0AIT].
Lie Groups and Lie Algebras, chapter III, § 9. Commutators, centralizers and normalizers in a Lie group
Let be a finite-dimensional Lie group, its Lie algebra and a subset of . Then is a Lie subgroup of with Lie algebra .
This follows from § 3, Proposition 44 and Corollary 2 to Proposition 39.
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.