For Those who are Farthest Away from Masjid
[Sahih Bukhari: Volume 1, Book 11, Number 623]
Narrated Abu Musa (Radi Allah Anhu): The Prophet (sal-allahu-alleihi-wasallam) said, "The people who get tremendous reward for the prayer are those who are farthest away (from the Masjid) and then those who are next farthest and so on. Similarly one who waits to pray with the Imam has greater reward than one who prays and goes to bed. "
For Pronouncing Azaan & Standing in First Row
[Sahih Bukhari: Volume 1, Book 11, Number 589]
Narrated Abu Huraira (Radi Allah Anhu): Allah's Apostle (sal-allahu-alleihi-wasallam) said, "If the people knew the reward for pronouncing the Azaan and for standing in the first row (in congregational prayers) and found no other way to get that except by drawing lots they would draw lots, and if they knew the reward of the Zuhr prayer (in the early moments of its stated time) they would race for it (go early) and if they knew the reward of 'Isha' and Fajr (morning) prayers in congregation, they would come to offer them even if they had to crawl."