1 Corinthians 14:9

Bible in Basic English 1965

So if you, in using a strange tongue, say words which have no sense, how will anyone take in what you are saying? for you will be talking to the air.

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There are, it may be, a number of different voices in the world, and no voice is without sense.

So then I am running, not uncertainly; so I am fighting, not as one who gives blows in the air: