Verses with the word speechless in the New Testament (3 verses):

Matthew 22:12
And he saith unto him, Friend, how camest thou in hither not having a wedding garment? And he was speechless.

Luke 1:22
And when he came out, he could not speak unto them: and they perceived that he had seen a vision in the temple: for he beckoned unto them, and remained speechless.

Acts 9:7
And the men which journeyed with him stood speechless, hearing a voice, but seeing no man.