Performed the Maghrib prayer and realised he had not performed the ‘Asr prayer
Question: If one remembers that he has not performed the ‘Asr (prayer) except after having performed the Maghrib (prayer), should he (then) perform the ‘Asr (prayer) and (then) the Maghrib(prayer) or should he (suffice with) perform the ‘Asr (prayer) only?
Response: He should only perform the ‘Asr prayer, because he has performed the Maghrib(prayer) at its time, and likewise (it is considered) he has performed the ‘Asr (prayer) at it’s time since it’s time is (considered as such) when one remembers (not having performed it).
Shaykh al-Albaanee
al-Haawee min Fataawa ash-Shaykh al-Albaanee – Page 187 fatwaonline.com