The most grievous torfnent for the people on the Day of Resurrection would be for those who try to imitate Allah in the act of creation.  

دَخَلَ عَلَىَّ رَسُولُ اللَّهِ ﷺ وَأَنَا مُتَسَتِّرَةٌ بِقِرَامٍ فِيهِ صُورَةٌ فَتَلَوَّنَ وَجْهُهُ ثُمَّ تَنَاوَلَ السِّتْرَ فَهَتَكَهُ ثُمَّ قَالَ إِنَّ مِنْ أَشَدِّ النَّاسِ عَذَابًا يَوْمَ الْقِيَامَةِ الَّذِينَ يُشَبِّهُونَ بِخَلْقِ اللَّهِ  

"The Messenger of Allah [SAW] entered upon me, and I had put up a curtain on which there were images. When he saw it, his face changed color, then he tore it down with his hand and said: 'The people who will be most severely punished on the Day of Resurrection will be those who try to imitate the creation of Allah.'"  

عَنْ عَائِشَةَ زَوْجِ النَّبِيِّ ﷺ قَالَتْ دَخَلَ عَلَىَّ رَسُولُ اللَّهِ ﷺ وَقَدْ سَتَّرْتُ بِقِرَامٍ فِيهِ تَمَاثِيلُ فَلَمَّا رَآهُ تَلَوَّنَ وَجْهُهُ ثُمَّ هَتَكَهُ بِيَدِهِ وَقَالَ إِنَّ أَشَدَّ النَّاسِ عَذَابًا يَوْمَ الْقِيَامَةِ الَّذِينَ يُشَبِّهُونَ بِخَلْقِ اللَّهِ  

The most grievous torfnent for the people on the Day of Resurrection would be for those who try to imitate Allah in the act of creation. (Using translation from Muslim 2107f)   

دَخَلَ النَّبِيُّ ﷺ وَأَنَا مُسْتَتِرَةٌ بِقِرَامٍ فِيهِ صُورَةٌ فَهَتَكَهُ ثُمَّ قَالَ إِنَّ أَشَدَّ النَّاسِ عَذَابًا يَوْمَ الْقِيَامَةِ الَّذِينَ يُشَبِّهُونَ بِخَلْقِ اللهِ ﷻ  

"The Messenger of Allah [SAW] entered upon me, and I had put up a curtain on which there were images. When he saw it, his face changed color, then he tore it down with his hand and said: 'The people who will be most severely punished on the Day of Resurrection will be those who try to imitate the creation of Allah.'" (Using translation from Nasāʾī 5357)   

عَنْ عَائِشَةَ دَخَلَ عَلَيَّ رَسُولُ اللهِ ﷺ وَقَدِ اسْتَتَرْتُ بِقِرَامٍ فِيهِ تَمَاثِيلُ فَلَمَّا رَآهُ تَلَوَّنَ وَجْهُهُ وَقَالَ مَرَّةً تَغَيَّرَ وَجْهُهُ وَهَتَكَهُ بِيَدِهِ وَقَالَ أَشَدُّ النَّاسِ عَذَابًا عِنْدَ اللهِ ﷻ يَوْمَالْقِيَامَةِ الَّذِينَ يُضَاهُونَ بِخَلْقِ اللهِ جَلَّ وَعَزَّ أَوْ يُشَبِّهُونَ قَالَ سُفْيَانُ سَوَاءٌ  

[Machine] The Messenger of Allah ﷺ entered upon her while she was covered with a curtain that had statues on it. The face of the Messenger of Allah ﷺ changed color and he turned away from the curtain, tearing it with his hand. Then he said, "Indeed, the severest punishment on the Day of Resurrection will be for those who create images resembling the creation of Allah."  

أَنَّ رَسُولَ اللَّهِ ﷺ دَخَلَ عَلَيْهَا وَهِيَ مُسْتَتِرَةٌ بِقِرَامٍ فِيهِ تَمَاثِيلُ فَتَلَوَّنَ وَجْهُ رَسُولِ اللَّهِ ﷺ وَأَهْوَى إِلَى الْقِرَامِ فَهَتَكَهُ بِيَدِهِ ثُمَّ قَالَ «إِنَّ أَشَدَّ النَّاسِ عَذَابًا يَوْمَ الْقِيَامَةِ الَّذِينَ يُشَبِّهُونَ بِخَلْقِ اللَّهِ»