Excerpts from the 1689 LBC...

Prayer, with thanksgiving, being one part of natural worship, is by God required of all men. But that it may be accepted, it is to be made in the name of the Son, by the help of the Spirit, according to his will; with understanding, reverence, humility, fervency, faith, love, and perseverance; and when with others, in a known tongue. ( Psalms 95:1-7; Psalms 65:2; John 14:13, 14; Romans 8:26; 1 John 5:14; 1 Corinthians 14:16, 17 ) ​​Chapter 22, Paragraph  3.