Is the prostration of forgetfulness (sujud al-sahw) obligatory for someone who doubts or remembers that they forgot the Ibrahimiyyah prayer (Salat al-Ibrahimiyyah) after the adhkar (remembrances) of the prayer and before the taslim (salutation), so they return and perform it?

Sending blessings upon the Prophet (peace be upon him) is a pillar of prayer in the final Tashahhud according to some scholars. Whoever doubts having performed it should do so and perform the prostration of forgetfulness (sujud al-sahw). As for someone who remembers having omitted it before the salutations of peace, after having inadvertently recited some supplications, they should make up for it. Scholars have differed regarding the legitimacy of the prostration of forgetfulness in this case, but omitting it does not invalidate the prayer.