Beginning in chapter 12 and through this chapter 14, he is addressing speaking in tongues and mostly comparing/contrasting this gift of the Spirit and its appropriate use with the gift of prophesying. In particular, they were using miraculous gifts of tongues improperly (with no interpreter – vs 27). Since there was no interpreter, it was not useful for the “building up” of the church (vs 5), therefore it wasn’t to be done (without an interpreter).
Here he quotes Isaiah 28:11 and the later part of 28:12 (which is a similar thought to what Moses said in Deuteronomy 28:49). In both cases, the respective contexts are talking about the judgment/captivity of the people.