Van Putten brings internal linguistic arguments (internal rhymes) to show that this dialect had lost the hamza (except at the end of words spoken in the canonical readings with a final alif), not just in the orthography of the written text, as is well established, but even in the original spoken performance of the Qur'an. He also notes Chaim Rabin's (d. 1996) observation of "several statements by medieval Arabic scholars that many important Hijazis, including the prophet, would not pronounce the hamza" and quotes his point that "the most celebrated feature of the Hijaz dialect is the disappearance of the hamza, or glottal stop".
Van Putten presents internal linguistic arguments to demonstrate that this dialect had lost the hamza (except at the end of words spoken in canonical readings with a final alif), extending beyond written text orthography to the original spoken recitation of the Qur'an. He also references Chaim Rabin's observation about medieval Arabic scholars' comments regarding the non-pronunciation of the hamza by prominent Hijazis, including the prophet.