1 Corinthians 14:16
Else when thou shalt bless with the spirit, how shall he that occupieth the room of the unlearned say Amen at thy giving of thanks, seeing he understandeth not what thou sayest? Else when thou shalt bless with the spirit, how shall he that occupieth the room of the unlearned say Amen at thy giving of thanks, seeing he understandeth not what thou sayest?
Paul is dealing with blessing or praying with the spirit in an unknown tongue without interpretation, which leaves the understanding unfruitful. Prayer is to be with the spirit and with the understanding also, and one who speaks in an unknown tongue is to pray that he may interpret. In the church five words spoken with understanding to teach others are better than ten thousand words in an unknown tongue.
Even when thanks is given well, if the one occupying the room of the unlearned does not understand what is said he cannot say Amen at the giving of thanks and he is not edified. All religious services and conduct must edify others, strengthen those who take part, and work for the perfection of the church. The same rule that governs the gift of tongues governs the voice in prayer and social meeting. Blessing, thanksgiving, prayer, testimony, and Bible reading in public worship, family worship, and gatherings must be spoken in clear, distinct, audible utterance that others can hear and understand, so they can join in, affirm with Amen, and be edified.
Public prayer is to be spoken slowly, clearly, distinctly, and loudly enough for everyone present to hear and understand, so they can blend their supplications with the prayer and unite in saying Amen. Praying with the face bowed down in a low, feeble, indistinct voice that cannot be heard is not edifying in family or public worship, and since nearly all can speak loud enough to be heard in ordinary conversation, they should do so when called to pray or testify. Prayer offered indistinctly, in too low a tone, or so hurriedly that words are jumbled together so that an interpreter is needed does the hearers no good, does not bless them, and dishonors God. Sinking the voice is no evidence of humility.
Public prayer is to use simple language rather than high-flown language, so those listening can understand what is said and unite with the petition. This standard applies to prayer in the pulpit, in the family circle, and in secret, with special force for public prayer. The voice should be consecrated to God and cultivated for this clear speech, and speaking in a low indistinct way should be regarded as a defect to be earnestly overcome in order to honor God, glorify Him, make the truth plain, edify His children, and bless the hearers. Ministers and all who offer public prayer must learn to pray this way, yet no one with defective voice should cease offering public prayer or bearing witness to Christ, for there is already too much silence in meetings. Such quiet, low prayer is appropriate for the closet in secret devotion, but not for family or public worship.