Playing around with dead bodies, proudly taking pictures beside decapitated heads, putting the flag above the dead bodies, putting your feet on dead bodies, speaking to decapitated heads.
The act of decapitation itself could be found in various verses but with focus on (sura Mohammed vers 4).
Now when ye meet the idolaters, then it is smiting of the necks until, when ye have routed them, then making fast of bonds; and afterward either grace or ransom till the war lay down its burdens. That (is the ordinance). And if Allah willed He could have punished them but that He may try some of you by means of others. And those who are slain in the way of Allah, He rendereth not their actions vain
Arabic Text
.إِذَا لَقِيتُمُ ٱلَّذِينَ كَفَرُواْ فَضَرۡبَ ٱلرِّقَابِ حَتَّىٰٓ إِذَآ أَثۡخَنتُمُوهُمۡ فَشُدُّواْ ٱلۡوَثَاقَ فَإِمَّا مَنَّۢا بَعۡدُ وَإِمَّا فِدَآءً حَتَّىٰ تَضَعَ ٱلۡحَرۡبُ أَوۡزَارَهَاۚ ذَٲلِكَ وَلَوۡ يَشَآءُ ٱللَّهُ لَٱنتَصَرَ مِنۡہُمۡ وَلَـٰكِن لِّيَبۡلُوَاْ بَعۡضَڪُم بِبَعۡضٍ۬ۗ وَٱلَّذِينَ قُتِلُواْ فِى سَبِيلِ ٱللَّهِ فَلَن يُضِلَّ أَعۡمَـٰلَهُمۡ
Tafsir Ibn kather and Tafseer el tabari, says that this is how Muslims handel the enemy when the wage jihad, whenever they meet those who doesn’t believe in war (says nothing about defense just war) they should decapitate them and parade their dead bodies. Also we see that Ibn Katheer is arguing about some Imams when they said that the Imam or Ameer is not allowed to kill a prisoner of war. That this is not the right way as the prophet has killed Uqba and Nudiar which gives the imam every right to choose to kill the prisoners of war or do with them whatever he sees fit. As according to Souret el Hahsr 7 whatever the prophet says or command must be followed. Which makes the killing of the prisoner of war a better act than releasing him. (According to al tabari). Upon checking Ibn Katheer and al Kurtoby more or less the same has been found.
Did Mohammed also play with the dead bodies?
For that we approach the book “Kitab el bidaya wel nihaya for Ibn Katheer” chapter “el magasi” volume 3 p.292. There we read how Abi Gahl has died and what happened to his dead body.
This is the story according to Islamic history.
The killing of ABi gahl (Abu Al Hakam) was on the hand of a young an from Ansar, then Abd allah Ibn Massoud stood on his chest and held his beard, then he told him bad situation for you isn’t it you little Shepard?. Then he decapitated him and the head was taken and put between the hands of the prophet and with this head Allah healed the hearts of the believers.
Arabic Text.
فكان قتل أبي جهل على يدي شاب من الانصار، ثم بعد ذلك يوقف عليه عبد الله بن مسعود ومسك بلحيته وصعد على صدره حتى قال له لقد رقيت مرتقى صعبا يا رويعي الغنم، ثم بعد هذا حز رأسه واحتمله حتى وضعه بين يدي رسول الله فشفى الله به قلوب المؤمنين، كان هذا أبلغ من أن تأتيه صاعقة أو أن يسقط عليه سقف منزله أو يموت حتف أنفه والله أعلم.
The exact same story is to be read with more graphic detail in the interpretation of al Al Alousi for Souret al Alaq verse 15. There we also read about dragging dead bodies on he streets and how happy and over joyed the Prophet was when he held the head in his hands.