(41) باب كَرَاهِيَةِ تَأْخِيرِ الصَّلاَةِ عَنْ وَقْتِهَا الْمُخْتَارِ وَمَا يَفْعَلُهُ الْمَأْمُومُ إِذَا أَخَّرَهَا الإِمَامُ
Abu Dharr reported:
The Messenger of Allah (ﷺ) said to me: O Abu Dharr, you would soon find after me rulers who would make their prayers dead. You should say prayer at its prescribed time. If you say prayer at its prescribed time that would be a supererogatory prayer for you, otherwise you saved your prayer.
Reference: Sahih Muslim 648 b
In-book reference: Book 5, Hadith 302
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1354