After two rakahs, a person starts rising without the first sitting but is still physically nearer the seated position. The person returns and recites tashahhud.
Because the sitting remains recoverable at that stage, its obligation is fulfilled rather than treating it as a completed omission.
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Prostrations of Forgetfulness: Causes, Method, Missed Sittings and Doubts
After two rakahs, a person starts rising without the first sitting but is still physically nearer the seated position. The person returns and recites tashahhud.
Because the sitting remains recoverable at that stage, its obligation is fulfilled rather than treating it as a completed omission.