TARAWEEH PRAYER 8 OR 20 RAK'AHS?

  Bismillah Walhamdulillah Was Salaatu Was Salaam 'ala Rasulillah

As-Salaamu Alaikum Wa-Rahmatullahi Wa-Barakatuh

(a) Aisha (Allah be pleased with her) reports that the Prophet (Peace be upon him) never prayed more than 8 rak'aats in taraweeh, so how come nobody disapproves of 20?(b) Is it true that Umar (Allah be pleased with him) introduced it?

(a) As regards the taraweeh prayer - people agree that the Sunnah of the Prophet (Peace be upon him) and the best way is 11 rak'aats. As regards any addition - then this is DISAPPROVED of and DECLARED AS A BID'AH (A bad innovation) by Shaykh al-Albani and by a few earlier scholars - that being reported from Imam Malik, Ibn ul-Arabee and as-San'aanee (see Salat-ut-taraweeh of Shaykh al-Albani). 

(b) It is not true that Umar (Allah be pleased with him) either prayed or ordered 20 rak'aats. Rather he ordered Ubayy ibn Ka'b to lead the people with 11 rak'aats (al-Muwatta 1/137, with a Sahih Isnad).

I do not wish to go into much detail on this issue, but Insha'Allah a separate publication is what is really required, to show which opinion is the most correct. But any way it should be said that the vast MAJORITY of the scholars of hadith, Fiqh, and even the four Mujtahid Imams are in agreement that 20 rak'ahs are the most appropriate, followed by 3 rak'ahs of witr, and this is also the opinion of the Imam of the "Salafiyya", Ahmad ibn Taymiyya!

First, it should be said that the hadith reported from Aisha (Allah be pleased with her) about 11 rak'ahs is not at all to do with tarawee, according to the majority of scholars, but in fact concerns the number of rak'ahs of TAHAJJUD prayer! The hadith in question is as follows:- 

Narrated Abu Salama ibn Abdur Rahman that he asked Aisha (Allah be pleased with her), "How was the prayer of Allah's Apostle (Peace be upon him) in Ramadan?" She replied, "He did not pray more than eleven raka'at in Ramadan or in any other month. He used to pray four raka'at - let alone their beauty and length - and then he would pray four - let alone their beauty and length - and then he would pray three rak'aat (witr)." She added, "I asked, 'O Allah's Apostle! Do you sleep before praying the witr?' He replied, 'O Aisha, My eyes sleep but my heart does not sleep.'" (Bukhari, 3/230, English edn)

According to the author of "Fatawa Rahimiyyah", Mufti Abdur Rahim Lajpuri (vol. 1, pg. 275); in his defence of 20 rak'ahs of taraweeh:
 
"The commentator of al-Sahih al-Bukhari and the erudite traditionist, Shaykh Shamsud-Din al-Kermani (d. 786 AH; Rahimahullah) said: 'In the hadith (above), the tahajjud prayer is meant. Abu Salama's question and Hadrat Aisha's answer concerned the tahajjud.' He adds further: 'If the tahajjud prayer is not meant, then this tradition will be at variance with the tradition that states that the Holy Prophet (Peace be upon him) led twenty rak'ahs each for two nights, and in the case of such clash the tradition of twenty rak'ahs which is affirmative (muthbit) shall have precedence because according to the principles of hadith, the affirmative takes precedence over the negative (naaf)" (vide: Al-Kawakib ud-Durari Sharh Sahih al-Bukhari, vol. 9, pg 155-156). I say, does this not mean that people who perform 8 rak'ahs of taraweeh, should pray 20 rak'ahs instead? Since according to the principles of hhadith (as affirmed by al-Albani), "The affirmative takes precedence over the negative in certain cases." 

Conclusion

The matter is quite clear that the number of rak’ah of taraweeh during the time of the companions رضی اللہ عنھم was 20. This has been established through many narrations. While the four Imams (Abu Hanifa, Shafi’, Malik, Hanbal) disagree in the total number of raka’ah of taraweeh, none of them has given a figure below 20. Taraweeh being 8 rak’ah is not supported by any of them. The ‘ijma of the companions رضی اللہ عنھم holds to be the last word on this subject for the Prophet Muhammad ﷺ said that after him we should hold fast to the practices of the rightly guided khalifahs.