Pope Shenouda III
Prayer is the work of the heart, whether expressed in words or not.
It is lifting up the heart to God because the heart talks to God through feelings and emotions more than the mouth does with words. The heart may be lifted up to God without words.
Therefore, the sigh of the heart is a prayer before God, The heart’s longing to God is a prayer. Feelings of love towards God are a prayer. So prayer is a relationship between God and man. And if this hearty relationship does not exist, words would be of no use.