If after performing ṣalāt al‑iḥtiyāṭ one realises that the deficiency in the number of rakʿahs in his prayer was less than the number of rakʿahs in his ṣalāt al‑iḥtiyāṭ – for example, for the doubt between two and four rakʿahs, he performs two rakʿahs of ṣalāt al‑iḥtiyāṭ and later realises that he had performed three rakʿahs – in such a case, he must perform the [original] prayer again.