Explanation

‘Umar (may Allah be pleased with him) told those who were attending the Friday sermon that they “ate two offensive plants: onion and garlic”. Arabs use the word ''offensive” for objectionable and reprehensible words, actions, possessions, food, or people. This is established in a Hadīth that Jābir (may Allah be pleased with him) reported from the Prophet (may Allah's peace and blessings be upon him) who said: “Anyone who eats from this offensive tree let them not come close to our mosque.” [Muslim] “…onion and garlic”: Everything that has an offensive odor, such as radish, leeks, tobacco, and cigarettes are included here. Onions and garlic are mentioned in particular because they are eaten often. Leeks are stipulated in a Hadīth reported by Jābir ibn ‘Abdullāh (may Allah be pleased with him) and narrated by Muslim. So if anyone smelled of onion or garlic in the mosque, they would be ordered to be taken out as far as Al-Baqī‘, because it offends not only people but also the angels, as was related in an authentic Hadīth. In Ibn Mājah, we read: ''At the time of the Messenger of Allah (may Allah's peace and blessings be upon him) if a foul odor was detected on a man, I would see him seized by the arm and taken out to Al-Baqī‘.” “So anyone who [wants to] eat them, let them eliminate [their odor] by cooking.” This is because cooking eliminated the odor and if the odor is eliminated, one may enter the mosque because the reason for the prohibition no longer exists. Cooking onion and garlic thoroughly is required if someone wishes to enter the mosque for prayer or any other purpose. If it is not time for prayer, one may eat them raw. The command to cook them is meant to prevent offending others.