Mishkat al-Masabih 4 Prayer كتاب الصلاة 729

وَعَنْ أَبِي سَعِيدٍ قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يُصَلِّي الضُّحَى حَتَّى نَقُولَ: لَا يَدَعُهَا وَيَدَعُهَا حَتَّى نَقُولَ: لَا يُصليهَا. رَوَاهُ التِّرْمِذِيّ

Abu Sa’id said: God’s Messenger used to pray in the forenoon so often that we felt he would never stop doing so; then he would leave off doing so for so long that we felt he would never resume prayer at that time. Tirmidhi transmitted it.