What should I do now, knowing that I doubted the number of prostrations in the Fajr prayer, and it became preponderant in my mind that I had prostrated twice, so I completed my prayer and did not perform the prostration of forgetfulness, based on my assumption that it was a whisper from Satan, then I found the saying of Ibn Uthaymeen: "If one of you doubts in his prayer, let him seek what is correct and complete his prayer based on it, then let him give the salutation of peace, then prostrate twice"?

The relied-upon opinion among us is that whoever doubts in their prayer should build upon the minimum and perform the prostration of forgetfulness (sujud al-sahw) before the salutations (taslim). However, based on what Sheikh Ibn Uthaymeen preferred, what is necessary is to build upon the maximum (the predominant assumption), and then perform the prostration of forgetfulness after the salutations. If one omits the post-salutation prostration of forgetfulness out of ignorance, the prayer is valid, and nothing is required, because the prayer is not invalidated by omitting obligatory acts out of ignorance, nor by intentionally omitting the post-salutation prostration of forgetfulness. And according to the view that it is a Sunnah, there is no issue regarding the validity of the prayer.