1704 – ʿUmar ibn al-Khaṭṭāb (may Allah be pleased with him) once delivered the Friday sermon and said during it: “People! You are eating two plants that, in my view, are nothing but foul—onion and garlic. I saw the Messenger of Allah ﷺ, whenever he detected their odor on a man inside the mosque, order that the man be taken out to al-Baqiʿ. Whoever eats them, therefore, should first neutralize them by cooking them well.” Narrated by Muslim.

[Explanation]
The chapter cited here by the author—may Allah have mercy on him—in Riyad al-Salihin concerns rulings related to mosques. It prohibits anyone who has eaten onion, garlic, leek, or anything similar from coming near or entering the mosque until the smell is gone. Among the reports he mentions is the narration of ʿUmar ibn al-Khaṭṭāb (may Allah be pleased with him). Addressing the people on a Friday, ʿUmar said, “You eat these two plants, onion and garlic, whose odor I consider nothing but offensive.” He related that the Prophet ﷺ, when someone who had eaten from them entered the mosque, would command that the person be escorted out to al-Baqiʿ. Al-Baqiʿ is, as is well known, close to the Prophet’s Mosque, yet the individual would be taken that far as a form of discipline; it would have sufficed merely to usher him out of the mosque’s door, but for the purpose of admonishment he was led to that location, which is somewhat farther away. ʿUmar (may Allah be pleased with him) added: “Whoever eats them”—meaning, whoever intends to eat them—“let him deaden their odor by cooking them,” that is, let him cook them thoroughly, for once they are cooked the offensive smell disappears while their benefit remains.