[Kindly note that I'm only looking for the sunni view]
During a nikah, I know with evidences that the khutbah (sermon) is done with certain verses from the Qur'aan and hadeeth.
But I often find that the one who conducts the marriage reads out a formula speech known as ijab and qabool (i.e. offering and acceptance). However, I find it difficult to find a single hadeeth where this is done during a nikah. I witness where the conductor of the marriage holds the hand of the groom and the bride's walee and gets them to repeat some words.
Can someone please help me find the source for this action?