Hamor and Shechem gave consent themselves to be circumcised. To this perhaps they were moved, not only by the strong desire they had to bring about this match, but by what they might have heard of the sacred and honourable intentions of this sign, in the family of Abraham, which it is probable they had some confused notions of, and of the promises confirmed by it; which made them the more desirous to incorporate with the family of Jacob. He (Shechem) was more honourable than all the house of his father More highly esteemed by the people, which was the reason he prevailed so much with them in so strange a request.
Related Commentaries of Genesis 34:18
Genesis 34:18-19
18 And their words pleased Hamor, and Shechem Hamor's son.
19 And the young man deferred not to do the thing, because he had delight in Jacob's daughter: and he was more honourable than all the house of his father.