Corollary
Tag 0AIY, permanent. Cite it as [Bourbaki, Tag 0AIY].
Lie Groups and Lie Algebras, chapter III, § 9. Commutators, centralizers and normalizers in a Lie group
If , A is a Lie subgroup of G and is the identity component of . This identity component is a Lie subgroup with Lie algebra (Proposition 11) and hence is equal to A by § 6, no. 2, Theorem 2 (i).
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.