Asymptotic stability implies the existence of a strong Lyapunov function

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I am having trouble understanding the proof that asymptotic stability implies the existence of a strong Lyapunov function. Taken from the book "Differential Dynamical Systems", chapter 4, by James Meiss. The definitions are: enter image description here

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and the theorem is: enter image description here

is a strong Lyapunov function. This is the start of the proof: enter image description here I don't understand how asymptotic stability implies there exists such a "uniform" time $T(\rho)$. I do understand how for all $x\in U$ there exists some time $T(\rho, x)$ but don't understand how there exists a uniform $T(\rho)$ which does not depend on $x$.