Praying four optional rak`ahs before the `Asr Prayer is recommended, and there are many hadiths that confirm their virtue. This view is upheld by Shafi`i and Hanafi scholars.
Praying supererogatory Prayers that are backed by authentic Shari`ah proofs have great merits that a Muslim is advised not to miss.
By frequently praying the sunnah Prayers, a Muslim is obeying and following Prophet Muhammad (peace and blessings of Allah be upon him). Also, the sunnah Prayersmake up for one’s shortcomings while performing obligatory Prayers.
In addition, praying supererogatory Prayers that precede obligatory ones prepares worshippers to be fully concentrating while performing obligatory Prayers.
A Muslim is recommended to pray four rak`ahs before the `Asr Prayer, as confirmed by Shafi`i and Hanafi scholars. The four optional rak`ahs before the `Asr are sunnah ghair mu’akadah (i.e., an unconfirmed sunnah that the Prophet did not regularly maintain). This, however, does not contradict the merits of praying four rak`ahs before the `Asr.
Below are some hadiths that affirm the merits and virtues of praying four optional rak`ahs before the `Asr prayer:
1- `Ali (may Allahbe pleased with him) reported that the Prophet used to pray four rak`ahs before the `Asr, ending each two rak`ahs with a tasleem for angels, prophets, and the believers (An-Nawawi, Al-Majmu`).
2- Ibn `Umar (may Allahbe pleased withhim) reported that the Prophet said, “May Allah shower His mercy on the person who prays four rak`ahs before the `Asr Prayer.” (Abu Dawud and At-Tirmidhi)
However, `Ali reported that the Prophet used to pray two rak`ahs before the `Asr (Abu Dawud).
As there are various reports on the number of supererogatory rak`ahs before the `Asr Prayer, it becomes optional for one to pray two or four rak`ahs. Yet, praying four rak`ahs is better, since they entail more blessings and rewards from Allah.
Almighty Allah knows best.