Musannaf Ibn Abi Shayba 16:258

Abu Bakr narrated to us, he said: Ibn ‘Ulayyah narrated to us, from Sa‘id, from Qatadah, from Salim ibn Abi al-Ja‘d, from Ma‘dan ibn Abi Talhah, that ‘Umar ibn al-Khattab said: "You indeed eat two plants, which I do not see as anything but foul: this garlic and this onion. I used to see a man, during the time of the Messenger of Allah (may Allah bless him and grant him peace), whose scent would be detected from him, so he would be taken by the hand until he was brought out to al-Baqi‘. So, whoever must eat them, let him kill them by cooking."