What is the best way to advise worshipers who come to the mosque permeated by the smell of garlic and onions, and to clarify that this contradicts the prohibition of the Prophet, may Allah’s prayers and peace be upon him, without embarrassing them?

The prohibition of entering the mosque for those who have eaten garlic or onions is mentioned in authentic hadiths, such as the hadiths of Ibn 'Umar and Anas. The ideal way to advise such people is to post the fatwa containing these hadiths on the mosque's door or wall. The fatwa numbers are: 46100 and 36801. Alternatively, you can ask the imam of the mosque or the Friday preacher to speak about this issue.