Muwatta Malik, Book 43, Hadith 1593 (In-Book) ⓘ

Yahya related to me from Malik from Yahya ibn Said from Said ibn al-Musayyab that Umar ibn al-Khattab killed five or seven people for one man whom they had killed secretly by trickery. Umar said, "Had all the people of Sana joined forces against him, I would have killed them all."

وَحَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، أَنَّ عُمَرَ بْنَ الْخَطَّابِ، قَتَلَ نَفَرًا خَمْسَةً أَوْ سَبْعَةً بِرَجُلٍ وَاحِدٍ قَتَلُوهُ قَتْلَ غِيلَةٍ وَقَالَ عُمَرُ لَوْ تَمَالأَ عَلَيْهِ أَهْلُ صَنْعَاءَ لَقَتَلْتُهُمْ جَمِيعًا ‏.‏