He is the one who is singled out in all aspects of perfection such that nothing else shares with Him in these. It is obligatory upon the servants to single Him out alone in belief, saying and action by acknowledging His unrestricted perfection, His uniqueness and singling Him out alone for all types of worship
يَا صَاحِبَيِ السِّجْنِ أَأَرْبَابٌ مُّتَفَرِّقُونَ خَيْرٌ أَمِ اللّهُ الْوَاحِدُ الْقَهَّارُ
“O my companions in imprisonment! Which is more reasonable: [belief in the existence of numerous divine] lords, each of them different from the other” -or [in] the One God, who holds absolute sway over all that exists?
قُلْ هُوَ اللَّهُ أَحَدٌ
SAY: “He is the One God:
[Surat al Ikhlas]