بِسْــــــــــــــــــمِ اﷲِالرَّحْمَنِ اارَّحِيم
Abu Huraira reported that Allah’s Messenger (sal Allahu alaihi wa sallam) said to Bilal :
“Bilal, tell me which act you did at the time of the morning prayer for which you hope to receive good reward, for I heard during the night the sound of your footsteps before me in Paradise?”
Bilal (radi Allahu anhu) replied: “I did not do any act in Islam for which I hope to get any benefit, but this, that when I perform complete ablution during the night or day I observe prayer with that purification, what Allah has ordained for me to pray.”
[Sahih Muslim]
What Bilal (radi Allahu anhu) used to do is not that difficult to do. He would try to stay in a state of purity, and whenever he did wudhu or ghusl, he would pray nafl rakaat with that wudhu. This enabled his footsteps to precede those of Rasul Allah (sal Allahu alaihi wa sallam) in Paradise.