Anas reported that Allah's Messenger (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).
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، قَالَ ضَحَّى النَّبِيُّ صلى الله عليه وسلم بِكَبْشَيْنِ أَمْلَحَيْنِ أَقْرَنَيْنِ ذَبَحَهُمَا بِيَدِهِ وَسَمَّى وَكَبَّرَ وَوَضَعَ رِجْلَهُ عَلَى صِفَاحِهِمَا .
Muslim
The Book of Sacrifices • Hadith 24