Muwatta Malik, Book 3, Hadith 42 (USC-MSA) ⓘ
Yahya related to me from Malik from Hisham ibn Urwa that his father used to recite behind the imam when the imam did not recite aloud.
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، أَنَّهُ كَانَ يَقْرَأُ خَلْفَ الإِمَامِ فِيمَا لاَ يَجْهَرُ فِيهِ الإِمَامُ بِالْقِرَاءَةِ .
also referenced under: Book 3, Hadith 189 (In-Book)