To put one's foot on the side of the animal at the time of slaughtering

Sahih al-Bukhari · Book 73 · Hadith 5564

حَدَّثَنَا حَجَّاجُ بْنُ مِنْهَالٍ، حَدَّثَنَا هَمَّامٌ، عَنْ قَتَادَةَ، حَدَّثَنَا أَنَسٌ ـ رضى الله عنه ـ أَنَّ النَّبِيَّ صلى الله عليه وسلم كَانَ يُضَحِّي بِكَبْشَيْنِ أَمْلَحَيْنِ أَقْرَنَيْنِ، وَوَضَعَ رِجْلَهُ عَلَى صَفْحَتِهِمَا، وَيَذْبَحُهُمَا بِيَدِهِ‏.‏

Narrated Anas: The Prophet (ﷺ) used to offer as sacrifices, two horned rams, black and white in color, and used to put his foot on their sides and slaughter them with his own hands.