God Command
وَمِنَ اللَّيْلِ فَتَهَجَّدْ بِهِ نَافِلَةً لَكَ عَسَى أَنْ يَبْعَثَكَ رَبُّكَ مَقَامًا مَحْمُودًا
"and In some parts of the night (also) offer the Salât (prayer) with it (i.e. recite the Qur'an In the prayer), as an additional prayer (Tahajjud optional prayer Nawâfil) for You (O Muhammad ). it may be that Your Lord will raise You to Maqâman Mahmûda (a station of praise and glory, i.e. the highest degree In Paradise!)."
"and pray In the small watches of the morning: (it would be) an additional prayer (or spiritual profit) for thee: soon will Thy Lord raise Thee to a station of Praise and glory!"
Shalat Tahajjud : Al Israa' : 79
