If x∈Eh∩ dom(u), then the support of the spectral measure μx of x relative to u is contained in the interval [ϱe,+∞[ (Prop. 9, a) of IV, p. 278), hence
⟨x∣u(x)⟩=∫Rtdμx(t)⩾ϱe∥x∥2
Bourbaki sets the proof directly after the statement, and the corpus does not separate them, so what is above is the statement and its proof together.