Reference: al-Muntaqaa min Fataawa Shaykh Saalih al-Fowzaan – Volume 5, Page 39, Fatwa No.56
Question: What is to be said in the sajdah as-sahoo (the prostration of forgetfulness), and may Allaah reward you with good?
Response: One says in the sajdah as-sahoo (the prostration of forgetfulness) what one says in the prostration of the [regular] prayer, [namely] Subhaana Rabbee al-A’laa, and one supplicates as one does so in the prostration of the [regular] prayer – there being no difference between the two based upon the generality of the proofs/evidences, and there being no evidence that the prostration of forgetfulness has a specific supplication, and Allaah [alone] has the Complete knowledge [of all affairs].