the ChachakkaSutta:
“If anyone should say, ‘Feeling is self,’ that is not tenable. For an
arising and a falling away of feeling are discerned. Since its
arising and falling away are discerned, the consequence would
follow: ‘My self arises and falls away.’ Therefore it is not tenable
to say, ‘Feeling is self.’ Thus feeling is non-self”
…
“
If anyone says, ‘The mind is self,’ that is not tenable. The rise and fall of the mind are discerned, and since its rise and fall are discerned, it would follow: ‘My self rises and falls.’ That is why it is not tenable for anyone to say, ‘The mind is self.’ Thus the mind is not self.
(MN 148/M III
283).