If I accidentally recited SubhanAllah instead of reciting the Fatiha right away, must I perform the prostrations of forgetfulness?
In the Name of Allah, the Most Merciful and Compassionate
If you unduly delayed the recitation of Sura al-Fatiha such that you were not engaged in any of the actions of prayer in the period of that delay, the prostrations of forgetfulness are necessary. [Tahtawi,Shurunbulali; Hashiyat Maraqi al-Falah]
However, if the delay is short or you were engaged in some actions of the prayer (such as saying SubhanAllah) in that period of delay this does not necessitate a prostration since such delays are excused. [Ibn ‘Abidin, Radd al-Muhtar]
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani