Sneezing During Friday Sermon
Question

                What should a person do if he sneezes during the Jumu‘ah khutbah (sermon)? Should he say “al-hamdu Lillah”?.
Praise be to Allah.
    If a person who is 
    listening to the khutbah (sermon) on Friday sneezes, he should say “al-hamdu 
    Lillah (praise be to Allah)” quietly to himself. If anyone hears him, it is 
    not permissible for him to say to him “Yarhamuk Allah (may Allah have mercy 
    on you)”. 

    It says in 
    al-Mudawwanah (1/230): Maalik said concerning someone who sneezes when 
    the imam is delivering the khutbah that he should say “al-hamdu Lillah” 
    quietly to himself. No one should say “Yarhamuk Allah” to the one who 
    sneezed when the imam is delivering the khutbah.

    End quote. 

    Al-Mirdaawi (may 
    Allah have mercy on him) said: It is permissible for him to say Ameen to the 
    du‘aa’ and to say “al-hamdulillah” silently if he sneezes. End quote from 
    al-Insaaf, 2/418 

    Shaykh Ibn Baaz 
    (may Allah have mercy on him) said: If he sneezes, he has to praise Allah 
    (say “al-hamdu Lillah”) to himself and not raise his voice.

    End quote from 
    Majmoo‘ al-Fataawa, 12/411 

    Shaykh Ibn 
    ‘Uthaymeen (may Allah have mercy on him) said: If a member of the 
    congregation sneezes on Friday, he should say “al-hamdulillah” silently. If 
    he says it out loud and the people around him hear him, it is not 
    permissible for them to say “Yarhamuk Allah” to him.

    End quote from 
    ash-Sharh al-Mumti‘, 5/109 

    And Allah knows best.