The Prophet ﷺ forbade praying with one's hands on one's waist.  

أَنَّ النَّبِيَّ ﷺ نَهَى أَنْ يُصَلِّيَ الرَّجُلُ مُخْتَصِرًا  

"I prayed beside Ibn Umar and put my hand on my waist, and he did this to me-knocked it with his hand. When I had finished praying I said to a man: 'Who is this?' He said: "Abdullah bin Umar.' I said: 'O Abu Abdur-Rahman, why are you angry with me?' He said: 'This is the posture of crucifixion, and the Mesenger of Allah ﷺ forbade us to do this.'"  

لِي هَكَذَا ضَرْبَةً بِيَدِهِ فَلَمَّا صَلَّيْتُ قُلْتُ لِرَجُلٍ مَنْ هَذَا قَالَ عَبْدُ اللَّهِ بْنُ عُمَرَ قُلْتُ يَا أَبَا عَبْدِ الرَّحْمَنِ مَا رَابَكَ مِنِّي قَالَ إِنَّ هَذَا الصَّلْبُ وَإِنَّ رَسُولَ اللَّهِ ﷺ نَهَانَا عَنْهُ