What is the ruling on vocalizing in prayer?

It is sunnah for the Imam to recite audibly in prayers where audible recitation is prescribed, such as Fajr prayer, Friday prayer, Eid prayers, the first two rak'ahs of Maghrib and Isha prayers, Tarawih, and Witr in Ramadan. He recites silently in prayers where silent recitation is prescribed, such as Dhuhr and 'Asr prayers. As for the congregant (ma'mum), audible recitation is not prescribed for him.

As for the one praying alone (munfarid), it is sunnah for him to recite audibly in Fajr prayer and the first two rak'ahs of Maghrib and Isha. He has a choice between audible and silent recitation in night prayers, but he should not recite audibly if it causes annoyance to others. However, in Dhuhr prayer, 'Asr prayer, Duha prayer, the regular sunnah prayers (rawatib), and other daytime supererogatory prayers, the sunnah is to recite silently.