What is the ruling on verbally articulating the intention at the beginning of prayer?

Uttering the intention is an innovation (bid'ah) that has not been proven from the Prophet, peace and blessings be upon him, nor from his Companions. Some later scholars mistakenly thought that Imam Shafi'i's statement, "No one enters prayer except with dhikr," meant uttering the intention, but the correct understanding is that he meant the opening takbir (Takbirat al-Ihram).