All praise is due to Allah, peace and blessings be upon His Messenger.
According to the Shafite school of thought, it is impermissible for a Muslim to offer Taraweeh prayer (optional congregational prayer on the nights of Ramadan) in four Raka`s that are followed with one Tashahood. Prayer offered as such is invalid, and no reward is received by its performer based on the Prophet`s Hadith: "The prayers of the night are in twos (two Raka's followed by two Raka's and so on)." [Al-Bukhaari and Muslim]. The Prophet (PBUH) and his righteous companions offered it in twos since it is a prayer that has a certain manner and certain rulings. So, it is impermissible to change its fixed status in the Prophetic Sunnah.
Alkhateeb Al-Shirbini (May Allah have mercy on him) said: “Offering Taraweeh in four Raka`s followed with one Tasleem is invalid since it should be offered in twos." [Mughni Al-Muhtaj vol.3/pp.159].
The scholars of the four juristic schools confirmed the aforesaid opinion regarding the number of Raka`s in Taraweeh prayer. However, the Hanafites, the Malikites and the Hanbalites didn`t deliver a fatwa nullifying offering it in four Raka`s-as the Shafites did- rather, they considered it disliked.
Abu Salma bin 'Abdur Rahman narrated: I asked 'Aisha: "How is the prayer of Allah's Apostle during the month of Ramadan." She said: "Allah's Apostle never exceeded eleven Rakat in Ramadan or in other months; he used to offer four Rakat-- do not ask me about their beauty and length, then four Rakat, do not ask me about their beauty and length, and then three Rakat." Aisha further said "I said: 'O Allah's Apostle! Do you sleep before offering the Witr prayer?' He replied: 'O 'Aisha! My eyes sleep but my heart remains awake'!" Scholars interpreted this Hadith as: He (Allah`s Apostle) used to offer four Raka`s and make Tasleem after each two as said by Ibn Bat`tal (May Allah have mercy on his soul): Aisha`s (May Allah be pleased with her) saying that the Prophet (PBUH) said: ”prayed four” is based on his saying” [Agreed upon].
The prayers of the night (Taraweeh prayer) are in twos (two Raka's followed by two Raka's and so on).” In another narration on the authority of Aisha (May Allah be pleased with her) she said: “The Prophet(PBUH) used to offer eleven Raka`s for Witr prayer, and he made Tasleem between each two.” [Related by Al-Bukhari vol.3/pp.142]
Accordingly, we recommend Muslims to follow the Sharia-approved evidence and the opinions of the eminent Muslim scholars. We also recommend that they don`t follow the opinions that lead individuals to feel embarrassed in their prayer because it was offered in an invalid or a disliked manner. And Allah Knows Best.
