Jumma Prayer | - How to return salaams to one who offers his hand in greeting during the khutbah

If the imaam is preaching and someone greets you and offers hishand,
what is the ruling?
Praise be to Allaah.
Gesture to him if it is the time of the khutbah, andput your hand in
his, without speaking, because the Messenger of Allaah (peace and
blessings of Allaah be upon him) commanded us to listen to the
khutbah. He said, "If you say to your companion on Friday, 'Listen!'
when the imaam is preaching, then you have engaged in idle speech."
(Narrated by al-Bukhaari, al-Jumu'ah, 882; Muslim, al-Jumu'ah, 1404.
Agreed upon).
He described his enjoining something good as being "idle speech"
(laghw) at the time of the khutbah, so how about other kinds of
speech? And the Prophet (peace and blessings of Allaah be upon him)
said, according to a saheeh hadeeth, "Whoever playswith the pebbles
(on theground) has engaged in idle speech (laghw)." (Narrated by
Muslim, al-Jumu'ah, 1419)
At Jumu'ah prayers, the believer should listen to the khutbah and be
humble and solemn, he should beware of playing with pebbles on the
ground or anything else. If someone greets him he should gesture tohim
without speaking. Ifhe puts his hand in his when he offers his
hand,without speaking, that isOK, as stated above. He should tell him
after the khutbah that he should not have done that, and that which is
prescribed if one comes in when the imaam is preaching is to pray two
rak'ahs to "greet the mosque" and not to say salaams to anyone until
after the khutbah has ended. If hesneezes he should praiseAllaah (say
"al-hamdu Lillah") to himself without speaking out loud.