Surah 2:238 of the ZSE (Zaid Standard Edition of the Qur'an) reads as follows: "Attend constantly to prayers and to the middle prayer and stand up truly obedient to Allah."
So we have (1) "prayers," and (2) "the middle prayer."
According to Aisha, something is missing from this Ayah in the ZSEQ.
Jami At-Tirmidhi 2982--Abu Yunus, the freed slave of Aishah, said: "Aisha ordered me to write a Mushaf for her, and she said: 'When you get to this Ayah then tell me: Guard strictly (the five obligatory) prayers, and the middle Salat.' So when I reached it, I told her and she dictated to me: 'Guard strictly (the five obligatory) prayers, and the middle Salat, and Salat Al-Asr. And stand before Allah with obedience.' She said: 'I heard that from the Messenger of Allah.'"
Thus, according to the Mother of the Faithful, when Muhammad recited this Ayah, it referred to (1) "prayers," (2) "the middle prayer," and (3) "Salat Al-Asr." The Ayah we have in the Zaid Standard Edition, then, is not the same as the Ayah that Muhammad recited. And yet, somehow, the Qur'an has been perfectly preserved!