Is it part of the Sunnah for a bayaan to be given when a nikah is performed.

Answer

A Nikah has no relationship with a bayaan. No one is required to sit for the bayaan given on the occasion of a nikah. At your place, the bayaan

SILENT DUA

"Supplicate (make dua/call) on your Rabb with humility and silently."

(Qur‟aan).

"Remember when he (Zakariyya) called His Rabb (with) a silent dua."

(Qur‟aan)

Loud, congregational duas are nugatory of humility and in conflict with the command of Allah Ta‟ala. Such ostentatious dua is bid‟ah.

on the nikah occasion is bid‟ah.