Explanation
Expresses a strong negative suggestion or prohibition: 'should not', 'must not'.
Formation
Verb-dictionary form + ものではない
Detailed explanation
「～ものではない」 is used to indicate that something should not or must not be done. It often appears in written or formal contexts, meaning 'it is not proper to...' or 'you shouldn’t...'.
Examples
そんなことを言うものではありません。
Sonna koto o iu mono dewa arimasen.
You should not say such a thing.
公共の場で大声を出すものではない。
Koukyou no ba de oogoe o dasu mono dewa nai.
You should not raise your voice in public places.
彼の秘密を他の人に教えるものではありません。
Kare no himitsu o hoka no hito ni oshieru mono dewa arimasen.
You must not tell his secret to other people.
安全な場所では遊んでいいが、危険なところで遊ぶものではない。
Anzen na basho de wa asonde ii ga, kiken na tokoro de asobu mono dewa nai.
It's okay to play in safe places, but you should not play somewhere dangerous.
Practice
Grammar content sourced from hanabira.org.