Does the voluntary prayer have specific dhikr like the obligatory prayer?

Question:
May Allah reward you, Your Eminence, father. The questioner asks: Does the voluntary prayer have dhikr like the obligatory prayer? And is it permissible to add to the dhikr?

Answer:
The voluntary prayer is like the obligatory prayer in standing, recitation, bowing, and prostration. Saying "Subhan Rabbi al-Azim" in the bowing, "Subhan Rabbi al-A'la" in the prostration, and in the tashahhud. The voluntary prayer is like the obligatory prayer in its dhikr and its actions; they are the same. Yes.