What is the ruling on praying four rak'ahs of Tarawih with one taslim, what is the evidence for it, what is the proportion of those who do so, and is it prayed this way in the Two Holy Mosques and Al-Aqsa Mosque?

We have clarified the ruling on Tarawih prayer, its number of rak'ahs, and what has been reported from the predecessors. We are not aware of any opinion that allows for only four rak'ahs in Tarawih, but whoever prays four will be rewarded for it. The scholarly disagreement regarding praying Tarawih four rak'ahs at a time with a single salutation has been explained previously. Tarawih prayer is usually performed two rak'ahs at a time, but it may be found prayed four rak'ahs at a time with a single salutation. In the Two Holy Mosques, Tarawih prayer is currently performed as twenty rak'ahs, two rak'ahs at a time.