1- To arrive early. Abu Hurayrah (G. p. H) narrated that the Messenger of Allah (P. B. U. H) said:
"He who makes ghusl as that for janaba then goes (to the mosque) in the first hour (early), it is as though he sacrificed a camel (for the sake of Allah); and he who goes in the second hour, it is as if he sacrificed a cow; and he who goes in the third hour, it is as if he sacrificed a horned ram, and he who goes in the fourth hour, it is as if he had sacrificed a hen, and whoever goes in the fifth hour, it is as if he offered an egg.
And, when the imam comes out (to deliver the khutba), the angels present themselves to listen to the khutba"
[Al-Bukhari, Vol. 1, The Book of Friday Prayer, Chapter 4/841]
(pa: 243)
It is recommended to come on foot in tranquillity and dignity, and not to ride to the mosque unless for a reason.
Abu Hurayrah (G. p. H) narrated that the Messenger of Allah (P. B. U. H) said:
"If prayer is established do not run to it but walk in tranquillity and
pray whatever you catch-up with, and complete whatever you miss".
[Al-Bukhari, Vol. 1, The Book of Friday Prayer, Chapter 16/866].
The imam is recommended to come late in order to prepare the khutba.
2- To invoke Allah (G. B. H) and perform non-obligatory prayers if one arrives at the mosque before the khutba.
When the imam sits, it becomes forbidden to perform non- obligatory prayers, and it does not count even if he has not started the khutba yet.
Similarly, it is forbidden and void to pray when the imam sits in between the two khutbas.
Tha'laba ibn Abu Maiek (G. p. H) narrated:
"The sitting of the imam interrupts any non-obligatory prayer, and his talk puts an end to any other talk".
[Al-Bayhaqi, Vol. 3, page 193].
This does not apply to the prayer of greeting the mosque when one arrives while the imam is seated on the minbar.
One may perform it, in fact it is sunna, provided the imam is not at the end of his khutba, so as not to miss the beginning of the prayer
with the imam. One must make it brief and confine himself to two rak'as.
Jaber (G. p. H) narrated that the Messenger of Allah (P. B. U. H) said:
"When one of you arrives on Friday while the imam is delivering the khutba. Let him perform two rak'as and let him make them brief".
[Muslim, Vol. 2, The Book of Friday Prayer, Chapter 14/59].
3- To sit near to the imam. Aus ibn Aus (G. p. H) narrated that the Messenger of Allah (P. B. U. H) said:
"One who performs ghusl, arrives (at the mosque) at the beginning of the khutba and prayer, sits near the imam, and listens to the khutba attentively, gets for every step a full year's reward of fasting and tahajud".
[Al-Tirmithi, Vol. 2, The Books of Prayer, Chapter 356/496].
4- To listen attentively to the khutba and cease talking and invoking Allah (G. B. H) for one who is able to hear the imam.
One who is not, refrains from talking but not from invoking Allah. Allah (G. B. H)says: {When Quran is read, listen to it with attention. }[Al-A'raf: 204].
This verse was revealed about the khutba which was described with the word "Quran" because it includes Quran verses.
The meaning of the verse indicates the recommendation to forgo talking not the prohibition of talking.
Anas ibn Maiek (G. p. H) said: "A Bedouin came to the Messenger of Allah (P. B. U. H) on Friday, and said:
"0 Messenger of Allah (P. B. U. H) ! The livestock, off spring, and people have perished. '
So The Messenger of Allah (P. B. U. H) lifted his hands in du'a, and the people raised their hands in du'a with him..".
[Al-Bukhari, Vol. 1, The Book of Asking For Rain Prayer, Chapter 20/983].
It is obligatory to return one's salam, though it is makrooh to give salam. It is sunna to say "yarhamkumul-lah" (Allah (G. B. H) have mercy on you) if one sneezes, or to raise one's voice with the blessing on the Prophet (P. B. U. H) when the imam recites {Allah and His angels send blessing on the Prophet (P. B. U. H), 0 you who believe! Send your blessing on him, and salute him with all respect} [AI-Ahzab: 56], and whenever his name is mentioned even if the khatib does not do so.
Apart from this, keeping silent is recommended for the above mentioned saying of Allah (G. B. H) and the hadith of Abu Hurayrah (G. p. H), in
which he said: "The Messenger of Allah (P. B. U. H) said:
"One who perfects his wudu, then comes to the Friday prayer, and listens to the khutba attentively, has his sins between this Friday and the previous Friday and three days extra forgiven, and even touching the pebbles (during the khutba) is considered useless talk (unacceptable)".
[Muslim, Vol. 2, The Book of Friday Prayer, Chapter 8/27].