Holy Qur’an 57:28
مَا لَكُمْ لَا تُؤْمِنُونَ بِاللَّـهِ وَالرَّسُولُ يَدْعُوكُمْ لِتُؤْمِنُوا بِرَبِّكُمْ وَقَدْ أَخَذَ مِيثَاقَكُمْ إِن كُنتُم مُّؤْمِنِينَ
O ye that believe! Fear Allah, and believe in His Messenger, and He will bestow on you a double portion of His Mercy: He will provide for you a Light by which ye shall walk (straight in your path), and He will forgive you (your past): for Allah is Oft-Forgiving, Most Merciful.
Sahih Bukhari – Hadith
Narrated Abu Huraira: Allah’s Apostle stood up for the prayer and we too stood up along with him. Then a bedouin shouted while offering prayer. “O Allah! Bestow Your Mercy on me and Muhammad only and do not bestow it on anybody else along with us.” When the Prophet had finished his prayer with Taslim, he said to the bedouin, “You have limited (narrowed) a very vast (thing),” meaning Allah’s Mercy.