حَدَّثَنَا مُسْلِمُ بْنُ إِبْرَاهِيمَ، حَدَّثَنَا هِشَامٌ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم ضَحَّى بِكَبْشَيْنِ أَقْرَنَيْنِ أَمْلَحَيْنِ يَذْبَحُ وَيُكَبِّرُ وَيُسَمِّي وَيَضَعُ رِجْلَهُ عَلَى صَفْحَتِهِمَا ‏.‏

Narrated Anas: The Prophet (PBUH) sacrificed two horned rams which were white with black markings, slaughtered, and uttered: "Allah is Most Great." and mentioned Allah's name and placed his foot on their sides. Translation Not Available

Book reference: Sunan Abi Dawud Book 16 Hadith 2794
Web reference: Sunan Abi Dawud Book 15 Hadith 2788