﴿ بَلِ ٱللَّهَ فَٱعْبُدْ وَكُن مِّنَ ٱلشَّٰكِرِينَ ﴾

“Nay, but thou shalt worship God [alone], and be among those who are grateful [to Him]!”

(Nay, but Allah must thou serve) you must believe in Allah's divine Oneness, (and be among the thankful) for what Allah has bestowed upon you of prophethood, Scripture and Islam!