Birkat Hamazon

Question

Rabbi Abadi: In your father's Birkat Hamazon, I was wondering why the phrase "Ve'al habayit hagadol ve'haqadosh" was left out of the third berakha. In his teshuva, your father mentions that his nusach is based primarily on the Rambam, and the Rambam does have that phrase in his version. Additionally, the Gemara states explicitly (Berakhot 48b) that phrase as being instituted by Shelomo Hamelekh, so it must have been an important part of the old original short version. Thanks, Yossi