Anas reported that Messenger of Allah ﷺ sacrificed with his own hands two horned rams which were white with black markings reciting the name of Allah and glorifying Him (saying Allah-o-Akbar). He placed his foot on their sides (while sacrificing). (Using translation from Muslim 1966a)
أَنَّ النَّبِيَّ ﷺ ضَحَّى بِكَبْشَيْنِ أَقْرَنَيْنِ أَمْلَحَيْنِذَبَحَهُمَا بِيَدِهِ وَسَمَّى وَكَبَّرَ وَوَضَعَ رِجْلَهُ عَلَى صِفَاحِهِمَا