Sahih Muslim Book 4, Hadith Number 877.

Chapter : The command to observe prayer with tranquillity and calmness and forbiddance of making gesture with hands and lifting them while pronouncing salutation, and the completing of first rows and joining together well in them.

Abu Huraira reported: The Messenger of Allah (may peace be upon him) said: If the people were to know what excellence is there in the Adhan and in the first row, and they could not (get these opportunities) except by drawing lots, they would have definitely done that. And if they were to know what excellence lies in joining the prayer in the first takbir (prayer), they would have vied with one another. And if they were to know what excellence lies in the night prayer and morning prayer, they would have definitely come even if crawling (on their knees).