Corollary 1
Tag 0430, permanent. Cite it as [Bourbaki, Tag 0430].
Commutative Algebra, chapter I, § 2. Flat modules
Let be a commutative ring, two flat -modules. Then is a flat -module.
is a -bimodule and it is sufficient to apply Proposition 8 with .
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.