Question: What is the ruling on saying Takbīr immediately after prayer before istighfār?

Sheikh Suleiman Ar-Ruhayli, waffaqullāh, stated: "It is established from Ibn Abbas, may Allah be pleased with them, that he would recognise the end of the prayer by the Takbīr. The term "Takbīr" is general (مجمل); it can refer to the general remembrance (Dhikr) or specifically to saying "Allāhu Akbar." The Dhikr after prayer has been clarified in a detailed manner and does not include saying "Allāhu Akbar" immediately after Tasleem. What is authentically reported from the Prophet ﷺ in a detailed manner is that he would say: ((أستغفر الله)) "I seek forgiveness from Allah" after his Tasleem. Therefore, the preferred opinion among scholars is that the Sunnah immediately after the Tasleem is to seek forgiveness. As for the Takbīr, it refers to the general remembrance (Dhikr) and not specifically to saying "Allāhu Akbar."