Let G be a simple group over a global function field K, and let π be a cuspidal automorphic representation of G. Suppose K has two places u and v (satisfying a mild restriction on the residue field cardinality), at which the group G is quasi-split, such that πu is tempered and πv is unramified and generic. We prove that π is tempered at all unramified places Kw at which G is unramified quasi-split.The proof uses the Galois parametrization of cuspidal representations due to V. Lafforgue to relate the local Satake parameters of π to Deligne's theory of Frobenius weights. The main observation is that, in view of the classification of generic unitary spherical representations, due to Barbasch and the first-named author, the theory of weights excludes generic complementary series as possible local components of π. This in turn determines the local Frobenius weights at all unramified places. In order to apply this observation in practice we need a result of the second-named author with Gan and Sawin on the weights of discrete series representations.2 Laurent Clozel has pointed out that, in his review of Shahidi's article for Mathematical Reviews, Wee Teck Gan noted that the version of the Arthur Conjectures assumed in Shahidi's Theorem 6.2 includes the Ramanujan Conjecture for GL(n). For number fields this is quite far from being established, but for function fields this is due to Laurent Lafforgue [Laf02, Théorème VI.10].3 Here and elsewhere, we use this expression as shorthand for the condition that G, as an algebraic group over Kv, is unramified and quasi-split.