SB 3.12.30

naitat pūrvaiḥ kṛtaṁ tvad ye
 na kariṣyanti cāpare
yas tvaṁ duhitaraṁ gaccher
 anigṛhyāṅgajaṁ prabhuḥ
Word for word: 
na — never; etat — such a thing; pūrvaiḥ — by any other Brahmā, or yourself in any previous kalpa; kṛtam — performed; tvat — by you; ye — that which; na — nor; kariṣyanti — will do; ca — also; apare — anyone else; yaḥ — that which; tvam — you; duhitaram — unto the daughter; gaccheḥ — would go; anigṛhya — without controlling; aṅgajam — sex desire; prabhuḥ — O father.
Translation: 
O father, this performance in which you are endeavoring to complicate yourself was never attempted by any other Brahmā, nor by anyone else, nor by you in previous kalpas, nor will anyone dare to attempt it in the future. You are the supreme being in the universe, so how is it that you want to have sex with your daughter and cannot control your desire?
Purport: 

The post of Brahmā is the supermost post in the universe, and it appears that there are many Brahmās and many universes besides the one in which we are situated. One who fills this post must be ideal in behavior, for Brahmā sets the example for all living entities. Brahmā, the living entity who is the most pious and spiritually elevated, is entrusted with a post next to that of the Personality of Godhead.