Hadith : Oh Bilal I heard your footsteps in front of me in Paradise.

Bismillahirrahmanirrahim

Narrated Abu Huraira Radi Allahu Anhu At the time of the Fajr prayer the Prophet Sallallahu Alaihi Wasallam asked Bilal radi allahu anhu, Tell me of the best deed you did after embracing Islam, for I heard your footsteps in front of me in Paradise. 

Bilal Radi Allahu Anhu replied, "I did not do anything worth mentioning except that whenever I performed ablution during the day or night, I prayed after that ablution as much as was written for me. 

{Sahih Bukhari, Vol. 2, Book 21, Hadith 250}

It was Narrated from tamim dari may ALLAH be pleased with him that the Prophet Peace be upon him said The first thing for which A person will be brought to a account on the Day of Resurrection will be his prayer (Salah) . If it is complete then the voluntary ( Nawafil) prayer will also be recorded for him (As an increase) If it is not complete then Allah will say to his Angels Look and see wheather you find any voluntary (Nawafil) prayer for my slave and take them to make up what is lacking from his obligatory ( farz) prayers then All his deeds will be recokened in like manner 

{Sunan Ibn Majah, Volume 1, #1426 -Sahih}