Answered by Ustadha Noura Shamma, SunniPath Academy Teacher
What should I do if I stood up after my second rakah, forgetting to sit and say the tashahud? What if I forgot to sit at the end of the prayer? Do I have to make up the prayer or can I just make a forgetfulness prostration?
In the Name of Allah, the Most Merciful, the Most Compassionate
Peace and blessings on our beloved Prophet Muhammad, and on his companions, his folk and those who follow him until the end of time.
Let us answer the question, step by step.
For the one who stands up forgetfully from prostration in the second rakah without sitting for the tashahud:
1. If a person, is praying alone or is the Imam and is in the process of rising:
a) If they are closer to sitting (the lower limbs haven’t straightened and their back is still bent), they should return to sitting, say the tashahud and there is NO forgetfulness prostration at the end of the prayer.
b) If they are closer to standing (lower limbs are straight) or have stood up completely- they do NOT return to sitting; they complete their prayer and make the forgetfulness prostration at the end of the prayer.
2. If the person is praying behind an Imam, he returns to the sitting even if he completely stood up, because his role is to follow.
For the one who stands up from prostration in the last rakah without sitting for the final tashahud:
a) If he hasn’t gone into prostration for the new rakah, he returns to the sitting and makes a forgetfulness prostration at the end.
b) If he has made a prostration for the new rakah, if he was praying a fard prayer it is now invalidated and because a nafl prayer. He now must complete another rakah and makes the forgetfulness prostration at the end of the prayer.
NOTE: They must now pray their fard taking care to be caution and not repeat their forgetfulness.
Al-Maydani, Abdul Ghani al-Ghanimi. Al-Lubab fe Sharh al-Kitab. (Beriut: Dar al-Ma’arif) vol. 1, p.78-79.