(37) باب أَمْرِ الأَئِمَّةِ بِتَخْفِيفِ الصَّلاَةِ فِي تَمَامٍ
Abu Bakr b. 'Abd al-Rahman reported that he had heard Abu Huraira say that the Messenger of Allah (ﷺ) said like it, but he substituted" the aged" for 'the infirm".
Reference: Sahih Muslim 467 d
In-book reference: Book 4, Hadith 211
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 945