What is the reason why the noon and afternoon prayers are performed together in Arafat, and the evening and night prayers are performed together in Muzdalifa?
An exception to the rule that each prayer must be performed in its determined time is that when hajjis are in Arafat, they perform the prayers of noon and afternoon together within the time limits of the noon prayer and in Muzdalifa they perform the evening and night prayers together within the time limits of the night prayer.
Scholars unanimously agree on it because the practices and the words of the Prophet during the Farewell Hajj are strong enough to constrict the relevant verses and hadiths. Abdullah b. Masud (may Allah be pleased with him) is reported to have said, "I have never seen the Messenger of Allah performing a prayer outside its determined time, except for two prayers: he performed the noon and afternoon prayers together in Arafat and the evening and night prayers together in Muzdalifa." (Bukhari, Hajj, 99; Muslim, Hajj, 288; Tecrid-i Sarîh Translation, II, 487, 488, VIII, 374; A. Davudoğlu, Sahih-i Müslim Translation, İstanbul 1977, IV, 136)
During a hajj after the death of Hazrat Prophet, Abdullah b. Masud led the evening and night prayers together and then led the morning prayer at an early time; he said that the Prophet said, “The usual times of those two prayers, evening and night prayers, were changed in Muzdalifa. People must not come to Muzdalifa before the time for night prayer starts and they must not perform those two prayers at an early time. " (Bukhari, Hajj, 97; Ahmad b. Hanbal, V, 202; Asım Köksal, İslâm Tarihi, İstanbul (n.d.), XVII, 273, 274).