The Sahabah's consensus on 20 Raka’at of Taraweeh
وفي المغني عن علي أنه أمر رجلا أن يصلي بهم في رمضان بعشرين ركعة قال وهذا كالإجماع-
Translation: And in Mughni there is a Hadith of Hadhrat Ali (May Allah be well pleased with him) that he (Hadhrat Ali) commanded a person to lead the people in 20 Raka’at of Taraweeh in Ramadhan. In the explanation of this Hadith, Imam ‘Aini (May Allah shower His mercy on him) writes: This practice of the Sahabah is like their consensus.
(Umdatul Qari Sharh Sahih Bukhari, Kitab Ul Tahajjud)
Imam Zail‘ai (May Allah shower His mercy on him) writes:
Translation: Our proof is the Hadith which Imam Baihaqui (May Allah shower His mercy on him) has narrated with a rigorously-authenticated chain of narration that the Sahabah would offer 20 Raka’at of Taraweeh in the caliphate of Hadhrat ‘Umar (May Allah be well pleased with him). This practice continued in the eras of Hadhrat ‘Uthman and Hadhrat ‘Ali (May Allah be well pleased with him) and in this way the Sahabah came to a consensus (on 20 Raka’at Taraweeh).
Hadhrat Mulla Ali Qari (May Allah shower His mercy on him) writes in his commentary on Mishkaat Sharh Mirqaat:
لكن أجمع الصحابة على أن التراويح عشرون ركعة -
Translation: Nevertheless, the Sahabah have agreed that Taraweeh is of 20 Raka’at.
(Mirqat Ul Mafateeh, Kitab Us Salaat, Bab Qiyami Shahri Ramadhan)
Hadhrat Imam Sarkhisi Hanafi (May Allah shower His mercy on him) writes in Mabsut:
وَفِي اتِّفَاقِ الصَّحَابَةِ رِضْوَانُ اللَّهِ عَلَيْهِمْ عَلَى تَقْدِيرِ التَّرَاوِيحِ بِعِشْرِينَ رَكْعَةً دَلِيلٌ عَلَى أَنَّ الْوَاجِبَاتِ فِي الْيَوْمِ وَاللَّيْلَةِ عِشْرُونَ رَكْعَةً وَذَلِكَ لَا يَكُونُ إلَّا إذَا كَانَ الْوِتْرُ وَاجِبًا -
Translation: The consensus of the Sahabah on 20 Raka’at of Taraweeh is the evidence that all the Fardh and Wajib Salaat in the day and night add up to 20 and this number will be completed when Witr is considered as Wajib.
(Mabsut Sarkhisi, Kitab Us Salaat, Al Faslil Awwal Fi ‘Adadir Raka’at)