The Prophet salla Allahu alaihi wa sallam said that if a person oversleeps a prayer or forgets it, he should pray it as soon as he remembers it as there is no expiation for missing the prayer except this. From this hadeeth, scholars said that sleeping and forgetting a prayer can be expiated by praying immediately. They said that if a person deliberately postpones a prayer until the following prayer is due, he shouldn’t and he must not pray it as it wouldn’t be accepted from him because its time expired.