1 Corinthians 14:9
So likewise ye, except ye utter by the tongue words easy to be understood, how shall it be known what is spoken? for ye shall speak into the air.
Cross-reference
1 Corinthians 14:19
Parallel
In 1 Cor 14:19, Paul prioritizes five intelligible words over ten thousand in a tongue — reinforcing the need for clarity from 14:9.
1 Corinthians 14:2
Parallel
In 1 Cor 14:2, Paul says tongues are mysteries to humans — directly illustrating the 'speaking into the air' problem in 14:9.
1 Corinthians 9:26
Parallel
In 1 Cor 9:26, Paul uses 'beating the air' for futile effort — mirroring the 'speaking into the air' in 14:9.