What is the ruling on the imam's trilling (tarjee') in prayer, and is that considered an embellishment of the voice? And does it lead to the repetition of letters? And is it permissible for the imam to suddenly raise his voice during recitation?

Vocalizing (tarjīʿ) in recitation is part of voice beautification, as long as it does not reach the point of excessive prolongation (tamṭīṭ) that alters the meaning. It has been reported that the Prophet, peace and blessings be upon him, vocalized in his recitation, and the Companions described his vocalization by saying "aahh, three times." This indicates the permissibility of vocalization and melodies that delight hearts with a beautiful voice.

Vocalizing was a choice made by the Prophet, peace and blessings be upon him, not a necessity due to the swaying of a camel.

If one excessively prolongs (madd) and stretches (tamṭīṭ) to the extent that it alters the Qur'an, displaces words, or turns vowels into letters, then it is disliked, and some scholars have deemed it forbidden.

Changing the imam's vocal tone by raising and lowering the voice is permissible as long as there is no extravagance and its aim is to soften hearts.