Is one who prayed, but then doubted whether he had omitted a pillar or doubted his ritual purity, considered to have abandoned prayer?

If a Muslim doubts one of the pillars of prayer or ablution, there are two scenarios:

- If the doubt occurs after completing the act of worship, it should be disregarded and does not affect the validity of the worship.

- If the doubt occurs during the act of worship, he must build upon certainty. If he doubts a pillar while he is in the same rak'ah (unit of prayer), he should perform it. If he doubts a pillar from a previous rak'ah, he should nullify that rak'ah and perform a complete rak'ah in its place, then perform the prostrations of forgetfulness (sujud al-sahw) after the salutation (taslim). Similarly, if he doubts a pillar of ablution, he should perform it and all subsequent pillars.