How is the intention (niyyah) to be vocalized when performing a missed prayer (salat fa'itah), or the traveler's prayer (combining prayers), or when repeating a prayer?

Some scholars consider uttering the intention (niyyah) to be an innovation (bid'ah), citing that the Prophet (peace be upon him) did not utter it, nor did any of his Companions do so, nor did any of the Tabi'in or the four Imams deem it good. And whoever thinks that Imam Al-Shafi'i's mention of "dhikr in prayer" refers to uttering the intention has erred, for he only meant the takbirat al-ihram (the opening takbir). Although some scholars recommended uttering the intention (especially for those afflicted with waswas - obsessive doubts), the relied-upon opinion is that it is disliked absolutely. It is better for the worshiper not to utter the intention, but rather to suffice with the intention of prayer, because the place of intention is the heart. As for combining prayers, there is a difference of opinion regarding the necessity of intention for it. According to the view that requires it, a person's firm resolve in their heart suffices, without uttering it.