´Abdullah bin Mas'ud narrated that :` Allah's Messenger said: "Salatul-Wusta is the Asr prayer."
Related hadith on this topic
Explanation & Benefits
Shaykh Dr. Abdur Rahman Freywai
1:
Wusta (the middle prayer) is so called because it is situated between the prayers of the day and the night.
Source: Sunan al-Tirmidhi – Majlis ‘Ilmi Dar al-Da‘wah, New Delhi Edition, Page: 181