TIRMIDHI 477:
from Fuḍayl b. Marzūq —
"The Prophet would pray Ad-Duha until we would say: 'He will not leave it.' And he would leave it until we would say: 'He will not pray it.'"
الترمذي ٤٧٧:
عن فضيل بن مرزوق —
كَانَ نَبِيُّ اللَّهِ ﷺ يُصَلِّي الضُّحَى حَتَّى نَقُولَ لاَ يَدَعُ وَيَدَعُهَا حَتَّى نَقُولَ لاَ يُصَلِّي