Muwatta Malik, Book 20, Hadith 141 (USC-MSA)

Yahya related to me from Malik from Abdullah ibn Dinar that he used to see Abdullah ibn Umar sacrificing animals two at a time during hajj and one at a time during umra. He said, "I saw him sacrifice an animal during an umra outside the house of Khalid ibn Usayd, where he was staying. I saw him stick his spear in the throat of the animal he was going to sacrifice until the spear came out under its shoulder."'

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، أَنَّهُ كَانَ يَرَى عَبْدَ اللَّهِ بْنَ عُمَرَ يُهْدِي فِي الْحَجِّ بَدَنَتَيْنِ بَدَنَتَيْنِ وَفِي الْعُمْرَةِ بَدَنَةً بَدَنَةً ‏.‏ قَالَ وَرَأَيْتُهُ فِي الْعُمْرَةِ يَنْحَرُ بَدَنَةً وَهِيَ قَائِمَةٌ فِي دَارِ خَالِدِ بْنِ أَسِيدٍ وَكَانَ فِيهَا مَنْزِلُهُ ‏.‏ قَالَ وَلَقَدْ رَأَيْتُهُ طَعَنَ فِي لَبَّةِ بَدَنَتِهِ حَتَّى خَرَجَتِ الْحَرْبَةُ مِنْ تَحْتِ كَتِفِهَا ‏.‏

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also referenced under: Book 20, Hadith 844 (In-Book)