It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "A man's praying with the congregation is better than his praying at home or in the market by twenty-five degrees. And whoever performs ablution well and then comes to the mosque for the prayer, for each step he is raised one degree and one sin is erased, until he enters the mosque. When he enters the mosque, he remains in a state of prayer as long as he is waiting for the prayer. The angels supplicate for mercy for this servant as long as he remains sitting in the place where he prayed, saying: 'Allahumma irhamhu, Allahumma ighfir lahu' (O Allah, have mercy on him; O Allah, forgive him), as long as he does not harm anyone and does not lose his ablution."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4966