´Smurah bin Jundub narrated that :` the Prophet said: "Salatul-wusta is the Asr prayer."
Shaykh Dr. Abdur Rahman Freywai
English Commentary: 1: Regarding which prayer is meant by "the middle prayer" (salat al-wusta), various hadiths have been narrated. The correct opinion is that what is meant is the ‘Asr prayer (salat al-‘asr). This is also the view of the majority of the Companions and the Followers (Tabi‘in). Imam Abu Hanifah and Imam Ahmad have also adopted this position.
2: The well-known position of Imam Malik and Imam Shafi‘i is also this.
Note: (Supported by the previous hadith, this is sahih li-ghayrihi (authentic due to corroborating evidence). There is a difference of opinion regarding Hasan al-Basri’s hearing from Samurah radi Allahu anhu. Also, Qatadah and Hasan al-Basri are mudallis (those who sometimes conceal their sources), and this narration is by way of ‘an‘anah (ambiguous transmission)).
Source: Sunan al-Tirmidhi – Majlis ‘Ilmi Dar al-Da‘wah, New Delhi Edition, Page: 182