Language:
كتاب الأذان
10  
Call to Prayers (Adhaan)
(32)
Chapter: The superiority of offering the Zuhr prayer early
(32)
باب فَضْلِ التَّهْجِيرِ إِلَى الظُّهْرِ
Sahih al-Bukhari 652, 653, 654

Narrated Abu Huraira:

Allah's Messenger (ﷺ) said, "While a man was going on a way, he saw a thorny branch and removed it from the way and Allah became pleased by his action and forgave him for that." Then the Prophet (ﷺ) said, "Five are martyrs: One who dies of plague, one who dies of an Abdominal disease, one who dies of drowning, one who is buried alive (and) dies and one who is killed in Allah's cause." (The Prophet (ﷺ) further said, "If the people knew the reward for pronouncing the Adhan and for standing in the first row (in the congregational prayer) and found no other way to get it except by drawing lots they would do so, and if they knew the reward of offering the Zuhr prayer early (in its stated time), they would race for it and if they knew the reward for `Isha' and Fajr prayers in congregation, they would attend them even if they were to crawl.

حَدَّثَنَا قُتَيْبَةُ، عَنْ مَالِكٍ، عَنْ سُمَىٍّ، مَوْلَى أَبِي بَكْرٍ عَنْ أَبِي صَالِحٍ السَّمَّانِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ بَيْنَمَا رَجُلٌ يَمْشِي بِطَرِيقٍ وَجَدَ غُصْنَ شَوْكٍ عَلَى الطَّرِيقِ فَأَخَّرَهُ، فَشَكَرَ اللَّهُ لَهُ، فَغَفَرَ لَهُ ‏"‏‏.‏ ثُمَّ قَالَ ‏"‏ الشُّهَدَاءُ خَمْسَةٌ الْمَطْعُونُ، وَالْمَبْطُونُ، وَالْغَرِيقُ، وَصَاحِبُ الْهَدْمِ، وَالشَّهِيدُ فِي سَبِيلِ اللَّهِ ‏"‏‏.‏ وَقَالَ ‏"‏ لَوْ يَعْلَمُ النَّاسُ مَا فِي النِّدَاءِ وَالصَّفِّ الأَوَّلِ ثُمَّ لَمْ يَجِدُوا إِلاَّ أَنْ يَسْتَهِمُوا لاَسْتَهَمُوا عَلَيْهِ ‏"‏‏.‏ ‏"‏ وَلَوْ يَعْلَمُونَ مَا فِي التَّهْجِيرِ لاَسْتَبَقُوا إِلَيْهِ، وَلَوْ يَعْلَمُونَ مَا فِي الْعَتَمَةِ وَالصُّبْحِ لأَتَوْهُمَا وَلَوْ حَبْوًا ‏"‏‏.‏
Reference : Sahih al-Bukhari 652, 653, 654
In-book reference : Book 10, Hadith 49
USC-MSA web (English) reference : Vol. 1, Book 11, Hadith 624
  (deprecated numbering scheme)