Is there a special supplication for one who intends to perform I'tikaf?

There is no specific supplication prescribed for someone intending to perform I'tikaf (spiritual retreat). Rather, they should occupy themselves with acts of worship such as dhikr (remembrance of God), prayer, recitation (of the Quran), and supplication. It is disliked for them to engage in other activities like studying or writing. Dhikr includes tasbeeh (glorification of God), tahleel (uttering "La ilaha illa Allah"), du'a (supplication), and tafakkur (contemplation).