I never saw the Messenger of Allah ﷺ pray the Duha prayer except on one occasion.
حدثنا وكيع قال حدثنا سفيان عن عاصم بن كليب الجرمي عن أبيه
ما رأيت رسول الله ﷺ صلى الضحى قط إلا مرة
Its chain of transmission is hasan. Asim bin Kulayb bin Shihab Jarmi is truthful, as is his father, and Sufyan bin Husayn, whose hadith we have already graded hasan.This hadith is supported by what Ayesha reported, "The Messenger of Allah never prayed the voluntary prayer of Duha, yet I pray it." And by the hadith, "I never saw him pray it on any other day but that one." And by the hadith, "He would not pray Duha unless he had come back from a journey."Bukhari related all of this in 3/56, number 1178 of Fath, in the book of tahajjud, chapter on praying Duha while at home, and Muslim in 1/497, number 717, in the book of the prayer of travelers. Ayesha explained the meaning of this, that it is a sunnah for us, and that the only reason the Messenger of Allah ﷺ did not pray Duha frequently was out of fear that it would be made obligatory upon the ummah.