Hadithcore
Mishkat al-Masabih, 1320

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.

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

References1 variant
In-Book Reference
Book 4, Hadith 729