MB 15: Even though etc. - Since it appears that he is bowing to an idol.
113:9. One may not add to the list of words used to describe The Holy One, Blessed be He [found in the first blessing of the Shmoneh Esrei]: "The great, mighty, and awesome Al-mighty." This prohibition applies only during the Shmoneh Esrei, because one is forbidden to change the language formulated by the Sages for the Amidah [lit. "One can not change the coin minted by the Sages"]. But with supplicatory prayers, requests and praises that a person says on his own, there is no such restriction. Nevertheless, it is proper for one who wishes to dwell on the praises of G-d to do so by reciting verses from Scripture [such as Psalms - LC].