Tirmidhi

Explanation:
1:
Guard your prayers, especially the middle prayer, and stand before Allah with devotion (al-Baqarah: 238).
2:
This recitation is irregular (shaadh), therefore it will not be considered. Alternatively, here the "waaw" is not for conjunction of difference, but rather it is a conjunction of explanation (tafsiri), so it will correspond with the next hadith, according to which the "middle prayer" (as-salat al-wusta) refers to the Asr prayer.

473. Commentary:

➊ The addition of "Salat al-Asr" by Aisha (radi Allahu anha) is, in fact, an explanation (tafsir) of "Salat al-Wusta," which has been transmitted from the Messenger of Allah (sallallahu alayhi wa sallam) in some hadiths; otherwise, these are not the words of the Noble Qur’an. "Salat al-Wusta" means the most virtuous prayer, and according to authentic hadiths, that is the Asr prayer. See: [صحیح البخاري ، الدعوات ، حدیث : 6396 ، وصحیح مسلم ، المساجد ، حدیث : 628]

Although some people have interpreted "Salat al-Wusta" to mean the middle prayer, in reality, any prayer can be considered the middle one. For example: Zuhr is in the middle of the day; Maghrib is the middle prayer in terms of the number of units (rak‘at); Isha is the middle prayer among the audible (jahr) prayers; Fajr is between night and day. Therefore, this interpretation does not seem correct.

410. Commentary:
➊ From this recitation, it is understood that by «صلوة الوسطي», what is meant is not the ‘Asr prayer but some other prayer, because conjunction (atf) necessitates distinction. However, the scholars have given three explanations for this hadith. The words of the noble verse mentioned in this hadith are, in technical terms, called “shaadh qira’ah” (irregular recitation), which is not authoritative. For the Qur’an, “tawatur” (mass transmission) is a condition. This type of recitation is helpful and supportive in explanation and clarification. Allamah Baji has said that it is possible that Aishah radi Allahu anha heard it from the Messenger of Allah sallallahu alayhi wa sallam, but later it was abrogated and she did not come to know of its abrogation. Or, she may have thought that the words of this verse remained while the ruling was abrogated. Or, it is also possible that the Prophet sallallahu alayhi wa sallam mentioned it as a virtue, but Aishah radi Allahu anha considered it to be the words of the Qur’an, and on this basis, had it written in her codex (mushaf).

➋ Or, this could be an explanatory conjunction (i.e., for clarification).

➌ Or, the “waaw” (conjunction) could be extra; this is also supported by the recitation of Ubayy ibn Ka‘b radi Allahu anhu, in which the words “salat al-‘asr” appear without the “waaw.” «والله أعلم .» (Awn al-Ma‘bood) The word (wustaa) is ambiguous. One meaning is general, i.e., “middle.” But another meaning is “the best and most superior,” as in the noble verse
«وَكَذَلِكَ جَعَلْنَاكُمْ أُمَّةً وَسَطًا لِتَكُونُوا شُهَدَاءَ عَلَى النَّاسِ» [البقره : 143]
“And thus We have made you a most excellent and superior community so that you may be witnesses over mankind.”
In this verse, “ummatan wasatan” means “the best and most superior community.” Similarly, the meaning of «الصلوة الوسطي» becomes “the best and most superior,” and a large number of hadiths indicate that by this, the ‘Asr prayer is meant.