Bismillaah:

The Hanafis say :

The prohibition of speech and prayer begins when the Imam appear , this is, after the first azaan and their proof is in the following Hadeeth.

Ruwiyah an Nabi صلى الله عليه وسلم :

'' When the Imam appears, there is to be no prayers or speech.''

Takhreej:

{ At Tabarani in al Kabir and declared as Maudu by Imam Dahaabhi , al Albaani, Al Hasan and others }

This hadeeth besides it being fabricated, it also contradicts the authentic narrations that obliged the performance of Tahihyatul masjid. It also contradicts the understanding of the Sahabah as can be seen in the following narration from the time of Umar رضي الله عنه .

The Shafiyah and Ahlul hadeeth say:

The prohibition of speech begins when the Imam start his speech, and their proof is in the following.

Thalabah ibn Abu Maalik رضي الله عنه said:

'' We would be talking on Friday while Umar was sitting on the minbar. When the Azaan was finished, Umar رضي الله عنه would stand and no one would utter a word until he had completely finished both his Khutbahs. When the Iqaamah was made and Umar came down from the Minbar, the people would speak.''

Takhreej:

{ Imam Ibn Abi Haatim in his Sunnan 1/201 and graded as Saheeh by Imam an Nawaawi, al Albaani, Al Hasan and others }

Imam Ahmad رحمه الله with his isnad relates:

'' Uthman bin Affan رضي الله عنه would speak to the people about their news and commodity prices while the iqaamah was being given.''

Takhreej:

{ Imam Al Haithami in his Majma az Zawaa'id 2/137 and he said its narrators are those of the Saheeh }

Imam Ash Shafi'i رحمه الله commented:

'' I believed that whoever attends the Khutbah should listen to it carefully and not speak, from the moment the Imam starts speaking till the second Khutbah is finished. One is however, permitted to speak while the Imam is standing on the Minbar and the Mu'azzin is calling the Azaan or after finishing it but before the Imam starts delivering the Khutbah. When the Imam starts, no one should speak till he finishes the second Khutbah.''

{ Al Umm 1/233, Tamaam ul Minnah pg 332, Al Mughni 2/169 }

*** And Allaah عزوجل knows best ***