The Groups
وَلَقَدْ أُوحِىَ إِلَيْكَ وَإِلَى ٱلَّذِينَ مِن قَبْلِكَ لَئِنْ أَشْرَكْتَ لَيَحْبَطَنَّ عَمَلُكَ وَلَتَكُونَنَّ مِنَ ٱلْخَـٰسِرِينَ
And it was already revealed to you and to those before you that if you should associate [anything] with Allah, your work would surely become worthless, and you would surely be among the losers."
Nearby ayahs help place verse 39:65 in sequence and meaning.
لَّهُۥ مَقَالِيدُ ٱلسَّمَـٰوَٰتِ وَٱلْأَرْضِ ۗ وَٱلَّذِينَ كَفَرُوا۟ بِـَٔايَـٰتِ ٱللَّهِ أُو۟لَـٰٓئِكَ هُمُ ٱلْخَـٰسِرُونَ
To Him belong the keys of the heavens and the earth. And they who disbelieve in the verses of Allah - it is those who are the losers.
قُلْ أَفَغَيْرَ ٱللَّهِ تَأْمُرُوٓنِّىٓ أَعْبُدُ أَيُّهَا ٱلْجَـٰهِلُونَ
Say, [O Muhammad], "Is it other than Allah that you order me to worship, O ignorant ones?"
بَلِ ٱللَّهَ فَٱعْبُدْ وَكُن مِّنَ ٱلشَّـٰكِرِينَ
Rather, worship [only] Allah and be among the grateful.
وَمَا قَدَرُوا۟ ٱللَّهَ حَقَّ قَدْرِهِۦ وَٱلْأَرْضُ جَمِيعًا قَبْضَتُهُۥ يَوْمَ ٱلْقِيَـٰمَةِ وَٱلسَّمَـٰوَٰتُ مَطْوِيَّـٰتٌۢ بِيَمِينِهِۦ ۚ سُبْحَـٰنَهُۥ وَتَعَـٰلَىٰ عَمَّا يُشْرِكُونَ
They have not appraised Allah with true appraisal, while the earth entirely will be [within] His grip on the Day of Resurrection, and the heavens will be folded in His right hand. Exalted is He and high above what they associate with Him.