Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.145.

Section : Sunnah acts of prayer, When The Prayer is to be Aloud or Subdued.

It is sunnah to recite aloud in the two rak’ah of the morning and the Friday congregational prayer, in the first two rak’ah of the evening and the night prayer, in the two ‘id prayers, the prayer for eclipses, and the prayer of asking for rain. The recital should be subdued during all of the noon and the afternoon prayer, during the last rak’ah of the evening prayer, and during the last two rak’ah of the night prayer. Concerning voluntary prayers, those made during the days should be subdued, while those made during the night can be either loud or subdued.