1 Corinthians 14:14

Overview - 1 Corinthians 14
Prophecy is commended,
and preferred before speaking with tongues,
by a comparison drawn from musical instruments.
12 Both must be referred to edification,
22 as to their true and proper end.
26 The true use of each is taught,
27 and the abuse taxed.
34 Women are forbidden to speak in church.
Treasury of Scripture Knowledge

1 Corinthians 14:14  (King James Version)
For if I pray in an unknown tongue, my spirit prayeth, but my understanding is unfruitful.

my spirit
1 Corinthians 14:2 1 Corinthians 14:15 1 Corinthians 14:16 1 Corinthians 14:19

That is, "not productive of any benefit to others."