Q. Why do we say, “Lord open my lips” before saying the Amidah?
A. The complete phrase, from Psalm 51:17, is “Lord, open my lips, and my mouth shall declare Your praise”. The Psalmist has sinned. He fears he will be unable to face or pray to God. If however the Almighty enables his lips to speak it will be an indication of forgiveness.
When the liturgy chose these words with which to approach the Amidah, it broadened the meaning to imply, “God, enter my mouth: help me to frame my prayers and to utter them sincerely”.
The person who prays dreads being tongue-tied and distracted. Without God’s help it may be too hard to pray. The result is a paradox – in our prayers God both speaks and is spoken to.