Is the prayer of one who performs the prostration of forgetfulness (sujud al-sahw) before the tasleem of the obligatory prayer, then performs the prostration of forgetfulness again after the supererogatory (sunnah) prayer due to obsessive doubt (waswasah), valid, or must it be repeated?

Scholars differ on the ruling concerning the takbirat al-intiqal (transition takbirs). The majority of scholars hold them to be Sunnah (recommended), while the Hanbalis consider them wajib (obligatory). If a worshiper doubts having missed a transition takbir, he is not required to perform the prostration of forgetfulness (sujud as-sahw), according to the relied-upon position of the Hanbali school. Thus, the prayer is valid in all cases. Doubt about an act of worship after completing it has no effect, and one should not give in to waswas (whispers/obsessive thoughts).