Hadith.924 - Muhammad ibn Imran asked Imam Jafar ibn Muhammad Al-Sadiq عليه السلام:
"For what reason is the recitation done aloud in the Jumu’ah prayer, the Maghrib prayer, the Isha prayer, and the Fajr prayer, while it is not done aloud in the Dhuhr and Asr prayers? And why is glorification (tasbih) in the last two rak‘ahs preferred over recitation?"
Imam عليه السلام replied: "When The Prophet صلى الله عليه وعلى آله وسلم was taken on the Night Journey to the heavens, the first prayer that Allah سبحانه وتعالى, the Exalted, ordained upon him was the Dhuhr prayer on the day of Jumu‘ah (Jumu’ah). Allah سبحانه وتعالى added angels to pray behind him and commanded His Prophet to recite aloud so that they would realize his excellence.
Then, Allah سبحانه وتعالى ordained the Asr prayer without adding any angels behind him, and He commanded him to recite quietly because there was no one behind him.
Next, Allah سبحانه وتعالى ordained the Maghrib prayer and added the angels to pray with him and commanded him to recite aloud, and the same applies to the Isha prayer. Near the time of Fajr, he descended, and Allah سبحانه وتعالى, the Exalted, ordained the Fajr prayer and commanded him to recite aloud so that people would know its excellence, just as He had shown it to the angels.
This is why it is recited aloud in these prayers. Tasbih became preferable to recitation in the last two rak‘ahs because, in those rak‘ahs, The Prophet صلى الله عليه وعلى آله وسلم, upon recalling the greatness of Allah سبحانه وتعالى, glorified Him, saying:
Subhana Allah, wal-hamdu lillah, wa la ilaha illa Allah, wa Allahu Akbar
“Glory be to Allah, and all praise is for Allah, and there is no deity except Allah, and Allah is the Greatest”
Therefore, tasbih became superior to recitation."