Muaza bint Abdullah Adawiya reported,

She asked Ayesha, "How many rakahs did the Messenger of Allah ﷺ pray for the Duha prayer?"Ayesha replied, "Four rakahs, and he would add as many more as he wished."

Azami 2922

Sahih

عن معاذة

أنها سألت عائشة: كم كان رسول الله ﷺ يصلي صلاة الضحى؟ قالت: أربع ركعات ويزيد ما شاء.

الأعظمي 2922صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Prayer
Chapter
Prayer of fear
Section
Recommendation of duha prayer, its minimum being two rakahs and its most complete form being eight rakahs
Numbering
Jami al-Kamil 2922 (2nd edition)
Azami 2922