Sefer HaBahir 4

1[Rabbi Berechiah continued,] "And what is the proof that this 'b'rachah' is from the word 'blessing' [baruch]? Perhaps it is from the language of [the word] 'knee' [berech]. As it is written, 'For to Me every knee will bend' (Isaiah 45:23). [God is] the Place [towards which] all knees bend. To what parable is this similar? To people who seek to see the face of the king, but do not know where His house is. First, they ask, 'Where is the house of the king?', and afterward [they can ask], 'Where is the king?' Therefore [it is written], 'For to Me every knee will bend' — even the highest ones — 'Every tongue will swear [loyalty to God]' (Isaiah 45:23)."