대잖아

'They said so, remember'

-대잖아 combines reported speech with an appeal to what you both already heard: 그러니까 아까 서까래에 유리가 있었대잖아 'that's what he said about the glass in the rafters.' The speaker is not making a new claim, only reminding you of someone else's. It is casual; two lines here add 요 for a polite version, -대잖아요.

Register: casual, reminding