Assuming the Imam of a congregational salat either doubts the number of units (rak’ahs) recited or recites the salat in error, the ma’mumin (those following the Imam in salat) may inform the Imam in relation to the number of units, or other duty, as long as they are certain. However, the manner of notifying the Imam must be such as to not invalidate one’s own salat; by way of example, valid methods include signalling by hand (e.g. clapping) or reciting a thikr (doxology) – such as Allahu Akbar etc. – aloud. Informing the Imam by merely speaking with him will invalidate one’s salat. Concerning the Imam, invalidatory factors vis-à-vis his salat include talking or turning away from the direction of the Qiblah. Assuming the Imam realises his error – via the above valid means – he ought to correct and then continue with the salat, thus accomplishing a valid salat without the need to either repeat or execute additional precautionary units. However, if the Imam does not realise his error, the followers may convert their niyyah into that of a singular, rather than congregational, salat. In other words, assuming the ma’mun notices the Imam’s error, he/she must endeavour not to invalidate one’s own.