What is the ruling for a lone worshipper (Munfarid) who doubts the number of units (rak'at) prayed?

Primary text

The apparent position of the madhhab dictates that a lone worshipper who doubts the number of rak'at offered must build upon certainty. This means the worshipper completes the number of rak'at confirmed as performed and disregards the uncertain portion. This is evidenced by the Hadith of Abd al-Rahman ibn Awf, where the Prophet, peace and blessings be upon him, instructed that if one doubts between two and one rak'ah, it is counted as one; between two and three, it is counted as two; and between three and four, it is counted as three. The worshipper must then complete the remaining portion of the prayer, ensuring any potential error lies in addition, followed by two prostrations (sujud) performed while seated before the final salutation (taslim). This ruling applies whether or not a contrary strong presumption exists, unless the doubt reaches the level of excessive obsessive whispering (waswas).