A Simple Way to Pray By Martin Luther
These are the Ten Commandments in their fourfold aspect, namely, as a school text, song book, penitential book, and prayer book. They are intended to help the heart come to itself and grow zealous in prayer.
Take care, however, not to undertake all of this or so much that one becomes weary in spirit. Likewise, a good prayer should not be lengthy or drawn out, but frequent and ardent. It is enough to consider one section or half a section which kindles a fire in the heart. This the Spirit will grant us and continually instruct us in when, by God’s word, our hearts have been cleared and freed of outside thoughts and concerns.
Nothing can be said here about the part of faith and Holy Scriptures [in prayer] because there would be no end to what could be said. With practice one can take the Ten Commandments on one day, a psalm or chapter of Holy Scripture the next day, and use them as flint and steel to kindle a flame in the heart.