Ultimately, metaphysics is a broad field with different topics, so if one were to say that the Buddha rejected all of metaphysics, I think that would be somewhat off the mark, as he is concerned with certain questions which might be termed metaphysical - depending on what definition you are using.
However, I think that it is fair to say he rejected quite a number of metaphysical views and taught that one should put aside and not bother with many other metaphysical questions.
So you're just going to have to be a bit more detailed in what you're trying to say here
Vayadhammā saṅkhārā appamādena sampādethā — All things decay and disappoint, it is through vigilance that you succeed — Mahāparinibbāna Sutta
Tārakā timiraṃ dīpo māyāvaśyāya budbudaḥ supinaṃ vidyud abhraṃ ca evaṃ draṣṭavya saṃskṛtam — A shooting star, a clouding of the sight, a lamp, An illusion, a drop of dew, a bubble, A dream, a lightning’s flash, a thunder cloud — This is the way one should see the conditioned — Vajracchedikā Prajñāpāramitā
I have seen all things that are done under the sun, and behold, all is vanity and a chase after wind — Ecclesiastes 1.14