Fathwa - Reciting Durood and kissing the thumbs during Khutba is not allowed

Q:How is it to kiss thumbs during Khutba upon hearing the name of
Rasool ALLAH peace beupon him and reciting Durood upon hearing the
Ayat-e-Durood?
A:During Khutba it is notallowed to perform Namaz or speak. In
Darmukhtar with Shami on page 158 in part two it is mentioned that *1.
When hear the name of Rasool ALLAH peace be upon him and
Ayate-e-Durood neither kiss the thumb nor recite Darood Shrif because
it is Fard to keep tounge silent (speechless), instead recite Darod
Shreef in heart. This order is for only during Khutba on other
ocassions it is Mustahib to kiss thumbs upon hearing the respectable
name of Rasool Allah Sallallahu Alaihe Wasslam. In Behr-ul-Ra'iq on
page 155 in part two it is mentioned that *2. In the same book on page
156 it is mentioned that *3. In Fataw-e- Amjadia on page 286 in part
one with refrence of Hidaya it is mentioned that *4. The same is also
mentioned in Fatawa-e-Rizvia on page 741 and 759 in part three. Allah
Ta'ala Knows the best.