Eleazar of Worms, Sefer Razi’el (Amsterdam, 1701), 8d

Jewish Mysticism
When a person prays he should direct his heart [with proper intention] as it says ‘I have placed the Lord before me always’ (Ps. 16-8). Therefore they established [in the formulation of blessings] ‘Blessed are You, Lord,’ like a person speaking to his friend.

Translated by Elliot Wolfson in Through a Speculum that Shines- Vision and Imagination in Medieval Jewish Mysticism, Princeton- Princeton University Press, 1994.