Among the rulings of the prostration of forgetfulness he states, while listing the occasions for which it is prescribed: “3. When the first tashahhud is omitted, or when any other sunnah element of the prayer is forgotten, on the strength of the report related by all the major compilers from Ibn Buhayna: the Prophet—peace and blessings be upon him—was praying; when he rose after two rakʿahs the people glorified Allah to alert him, but he went on. When he finished the prayer he performed two prostrations and then gave salām.”

I say: He has produced no evidence for prescribing the prostration when a sunnah element of the prayer is forgotten, and treating those sunnan as equivalent to the first tashahhud in this ruling is unsound for two reasons:

1. The first tashahhud itself is subject to disagreement regarding its obligatoriness, as has been explained in its proper place; therefore it is impermissible to attach to it something that is unanimously deemed recommended rather than obligatory.

2. The correct view is that the first tashahhud is in fact obligatory, for the Prophet ﷺ ordered the man who had prayed incorrectly: “When you sit halfway through the prayer, be at ease, place your left thigh on the ground, and then recite the tashahhud.” Abū Dāwūd transmitted it with a sound chain.