I was aware of one place
where Wittgenstein commented on Heidegger.
has shared another one with me, in "Wittgenstein’s Philosophical Conversations with Rush Rhees(1939–50): From the Notes of Rush Rhees
", edited by Gabriel Citron.
21. Reports of philosophical remarks of Wittgenstein’s, from
Rhees’s correspondence and notes
When I mentioned Heidegger to him once — I forget in what
connexion — Wittgenstein remarked that a man might be obscure
and still have something important to say; but he added: ‘But I
don’t trust Heidegger’.