Anas bin Malik (RA) reported: When we were in Madinah, the moment the Mu'adhdhin made the call to the sunset prayer, the people hastened to the pillars of the mosque and prayed two rak'ahs with the result that any stranger coming into the mosque would think that the obligatory prayer had been observed owing to the number who were praying then.
Explanation & Benefits
Shaykh Maulana Abdul Aziz Alvi
Hadith Commentary: Benefits and Issues: In the blessed era of the Prophet sallallahu alayhi wa sallam, there was great enthusiasm for virtue and much concern for the Hereafter. Therefore, the noble Companions radi Allahu anhum ajma'in would also be diligent in performing voluntary (nafl) prayers. As the desire for worldly wealth and possessions increased and people's occupations and engagements multiplied, the observance of such voluntary acts decreased. Consequently, in later periods, the two rak‘ahs before Maghrib began to be neglected, and as a result of this abandonment, some individuals even declared them to be an innovation (bid‘ah). Imam Malik rahimahullah and Imam Abu Hanifah rahimahullah also did not consider them to be a Sunnah. However, the abandonment of a Sunnah by people does not abrogate the Sunnah of the Prophet sallallahu alayhi wa sallam. When these two rak‘ahs are established by authentic ahadith and the authentic command of the Prophet sallallahu alayhi wa sallam is also present, then what doubt can there be regarding their recommendation?
Source: Tuhfat al-Muslim: Commentary on Sahih Muslim, Page: 1939