Sayyiduna Bara' bin Azib (may Allah be pleased with him) narrates from the Prophet (peace and blessings be upon him) that the Messenger of Allah (peace and blessings be upon him) would come to us when we stood up for prayer, and he (peace and blessings be upon him) would touch our shoulders and chests and say: "Do not differ, or your hearts will come to differ. Allah sends down mercy upon those in the first row, and the angels pray for mercy for them," or he said: "for the first rows."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5196