Pentecostals claim that a sign (sometimes the sign) of the baptism of the Holy Spirit is speaking in tongues, a reference to the events described in Acts 2. Oneness Pentecostals go further and claim that a person must speak in tongues to be saved. I have expressed my views on tongues-speaking elsewhere (use the "glossolalia" tag at the bottom).
I have a real problem with either assertion (especially that of Oneness).
Here is one reason why: "Jesus, full of the Holy Spirit, returned from the Jordan and was led by the Spirit in the wilderness" (Luke 4:1). This refers to His actions after His temptation by Satan. Note that it explicitly states that He was "full of the Holy Spirit." What it does not say is that He spoke in tongues.
What do the Pentecostals say about this passage? It belies their assertion about tongues. He didn't speak in tongues, yet the inspired commentary does not let us deny that He was filled with the Spirit. And it is even worse for the Oneness Pentecostals, because their doctrine means that Jesus needs to be saved. Surely it would be blasphemous to assert any such thing.
The solution is simple. There is no connection between tongues and the filling with the Holy Spirit. The circumstances in Acts (and mentioned nowhere else) reflect the transition from the the direct leadership of Jesus to His indirect leadership through the Apostles. The extraordinary signs were vindications of the Apostles, not the Spirit.