question #1 Sahih al-Bukhari 1683, Book 25, Hadith 163 : What is the significance of combining Maghrib and Isha prayers at Al-Muzdalifa during Hajj?

I went out with `Abdullah , to Mecca and when we proceeded to am’ he offered the two prayers (the
Maghrib and the `Isha’) together, making the Adhan and Iqama separately for each prayer. He took his
supper in between the two prayers. He offered the Fajr prayer as soon as the day dawned. Some
people said, “The day had dawned (at the time of the prayer),” and others said, “The day had not
dawned.” `Abdullah then said, “Allah’s Messenger (ﷺ) said, ‘These two prayers have been shifted from their
stated times at this place only (at Al-Muzdalifa); first: The Maghrib and the `Isha’. So the people
should not arrive at Al-Muzdalifa till the time of the `Isha’ prayer has become due. The second prayer
is the morning prayer which is offered at this hour.’ ” Then `Abdullah stayed there till it became a bit
brighter. He then said, “If the chief of the believers hastened onwards to Mina just now, then he had
indeed followed the Sunna.” I do not know which proceeded the other, his (`Abdullah’s) statement or
the departure of `Uthman . `Abdullah was reciting Talbiya till he threw pebbles at the Jamrat-Al-
`Aqaba on the Day of Nahr (slaughtering) (that is the 10th of Dhul-Hijja).