In SN 7.21, Ven. Ananda requested the Buddha to visit the home of the lay brahmin Sangarava and teach him, debunkingto debunk his belief in water purification rituals. The Buddha consented. The brahmin neither asked to be taught, nor approached the Buddha for any other reason.
In SN 7.22, the Buddha approached the council hall of Khomadussa where householders and brahmins were having a meeting. They saw the Buddha coming from a distance and mocked him as being a fake ascetic, to which he responded by giving them a teaching.