When the Buddha changes his mind to teach

I remember reading a sutta (possibly in Majjhima or Samyutta) where a passage has the Buddha talking about his teaching attitude towards certain people when talking to them. Then, he says something to the effect of "... but when a person is a fool, the Tathagata changes his mind". What sutta is this? I'm positive it's not AN 4.111, where there's an analogy with horse trainning: > “[...] But if a tamable person doesn’t submit either to a mild training or to a harsh training or to a mild & harsh training, then the Tathagata doesn’t regard him as being worth speaking to or admonishing.