The Groups
فَٱعْبُدُوا۟ مَا شِئْتُم مِّن دُونِهِۦ ۗ قُلْ إِنَّ ٱلْخَـٰسِرِينَ ٱلَّذِينَ خَسِرُوٓا۟ أَنفُسَهُمْ وَأَهْلِيهِمْ يَوْمَ ٱلْقِيَـٰمَةِ ۗ أَلَا ذَٰلِكَ هُوَ ٱلْخُسْرَانُ ٱلْمُبِينُ
So worship what you will besides Him." Say, "Indeed, the losers are the ones who will lose themselves and their families on the Day of Resurrection. Unquestionably, that is the manifest loss."
Nearby ayahs help place verse 39:15 in sequence and meaning.
قُلْ إِنِّىٓ أَخَافُ إِنْ عَصَيْتُ رَبِّى عَذَابَ يَوْمٍ عَظِيمٍ
Say, "Indeed I fear, if I should disobey my Lord, the punishment of a tremendous Day."
قُلِ ٱللَّهَ أَعْبُدُ مُخْلِصًا لَّهُۥ دِينِى
Say, "Allah [alone] do I worship, sincere to Him in my religion,
لَهُم مِّن فَوْقِهِمْ ظُلَلٌ مِّنَ ٱلنَّارِ وَمِن تَحْتِهِمْ ظُلَلٌ ۚ ذَٰلِكَ يُخَوِّفُ ٱللَّهُ بِهِۦ عِبَادَهُۥ ۚ يَـٰعِبَادِ فَٱتَّقُونِ
They will have canopies of fire above them and below them, canopies. By that Allah threatens His servants. O My servants, then fear Me.
وَٱلَّذِينَ ٱجْتَنَبُوا۟ ٱلطَّـٰغُوتَ أَن يَعْبُدُوهَا وَأَنَابُوٓا۟ إِلَى ٱللَّهِ لَهُمُ ٱلْبُشْرَىٰ ۚ فَبَشِّرْ عِبَادِ
But those who have avoided Taghut, lest they worship it, and turned back to Allah - for them are good tidings. So give good tidings to My servants