“Abu Ja’far (a.s.), was once asked about a man who performs Salah (prayer) without Tahur (cleansing) or forgets it (Salah (prayer)) or goes to sleep. He (the Imam) said, ’He performs its Qada’ (compensatory prayer) in whatever hour he remembers during the night or day. If the time for a Salah (prayer) comes and he has not yet completed what he was to perform as Qada’ (compensatory prayer) he completes what he is to do unless is afraid of running short of the time of Salah (prayer) of present time. Such Salah (prayer) is of greater priority in matters of its time thus, he performs it and when this is complete, he performs that which was missed in the past, and he does not perform any optional Salah (prayer) even one Rak’at, until completion of all obligatory ones.’”