Digha Nikaya (Coleção dos Discursos Longos) 1:163
SUJATOtatrassa dovāriko paṇḍito viyatto medhāvī aññātānaṁ nivāretā ñātānaṁ pavesetā.
And it has a gatekeeper who is astute, competent, and intelligent. He keeps strangers out and lets known people in.