In the presence of Imam (A.S.) or his specially appointed authority, Friday prayer is wajib al-‘ayni in place of Zuhr. Zuhr is not recited on such occasions.
In ghaybah (occultation) of the Imam (A.S.) when there is no one specially appointed by Imam (A.S.) to lead in this prayer, Friday prayer and Zuhr become wajib al-takhyiri.
Wajib al-takhyiri means that a man has an option to choose between two obligatory acts, but he cannot leave both. For example, in the 3rd and 4th rak’at of the daily prayers, a man has to recite either Tasbihat Arba’ah or Surah al-Hamd. He has to choose anyone of these two alternatives, but cannot leave both. Thus these two things are "wajib al-takhyiri" in these two rak’ats. Likewise, on Fridays, Zuhr and Friday prayer are wajib al-takhyiri. It means that a man has the option to choose between these two prayers. But he cannot neglect both.
There are certain conditions for Friday prayer:-
1. Friday prayer must be prayed in Jama’ah (congregation).
2. There must be at least 5 (better 7) persons including the Imam.
3. Only one Friday prayer may be prayed in a radius of 3 miles 720 yards. If two prayers are held within this distance, the later will be null and void.
According to the fatwa of Ayatullah al-Khu’i, if Friday prayer of even the Sunnis or other sects is held within the said radius of 3 miles 720 yards, and begins before the Friday prayer of the Shi’as, then those Shi’as who are followers of Ayatullah al-Khu’i cannot do niyyah of wajib for their Friday prayer. In such cases, they may pray Friday prayer with niyyah of qurbatan ilal-Laah (in the hope that may be the Shari’ah likes them to pray such Friday prayer) .
4. There must be two sermons delivered by the Imam before the prayer and attentively listened to by at least 4 (or 6) persons.
5. As explained earlier, it is not obligatory to hold Friday prayers specially. Instead, Zuhr may be prayed. But if Friday prayer is held by an ‘adil (just) lrnarn, then it is obligatory (ihtiyat wujubi) to participate In that prayer; and there will be no need to pray Zuhr afterwards. .
6. Friday prayer is two rak’ats: In the first rak’at it is sunnat for the Imam to recite Surah al-Jumu’ah and in the 2nd rak’at Surah al-Munafiqun, after Surah al-Hamd. .
7. Two qunut are mustahab in this prayer: In the 1st rak’at before ruku’; in the 2nd rak’at after rising from ruku’. There is a special qunut for Friday.
"Allahumma Inna ‘abidam min ‘ibadikas saleheena qamu bikitabika wa sunnati Nabiyyika fajzihim ‘anna khayr al-jaza". (O Allah, verily, some servants from among thy pious servants stood firm with Thy book and the traditions of Thy Prophet; Thou reward them with the best reward from us.)