Brachot 31 - How to pray
One should not start the Standing prayer (Amidah) unless he has put himself in a reverent frame of mind. The early pious ones would meditate for a complete hour before Amidah, to direct their minds to their Father in Heaven.
What is the source of this rule? - We can learn it from Hannah , who was "exceptionally bitter at heart." (Book of Samuel)? - No, that cannot be the source, perhaps Hannah had more problems than normal. Rather it is from the psalm: " As for me... I will prostrate myself in awe of You ." - No, that can't be the source either, maybe King David is trying to be exceptionally righteous. Rather, it is from here, " Serve God with awe and rejoice with trepidation ."
What does "rejoice with trepidation" mean? - That one should not loose the awareness of God even in supreme joy. Abaye was sitting and learning before Rabbah, and Rabbah noticed that Abaye was excessively cheerful. He said to Abaye, "Rejoice with trepidation!?" - Abaye answered, "I am wearing tefillin." Some say that Abbaye was joyful to finally be able to fulfill this mitzvah, and others - that tefillin themselves have a spiritual effect on a person.
Mar the son of Ravina made a wedding feast for his son, and he observed that the rabbis were excessively cheerful. He brought a precious glass cup worth four hundred zuz and broke it in front of them, and they were saddened.
The Talmud derives multple laws of prayer from the prayer of Hannah in the Temple.
Art: William Brassey Hole - The sorrow of king David