Abu Dawud
Prayer
Book Number: 002 / Hadith Number: 564
Narated By AbuHurayrah : The Prophet (pbuh) said: whoever performs ablution, and performs his ablution perfectly, and then goes to the mosque and finds that the people had finished the prayer (in congregation), Allah will give him a reward like one who prayed in congregation and attended it; The reward of those who prayed in congregation will not be curtailed.