〜てやまない

Meaning

Indicates holding a certain feeling strongly and endlessly. 「やまない」 is written 「止まない」, meaning "does not cease." Used only with a limited set of emotion verbs such as 「願う」 (wish), 「祈る」 (pray), 「愛する」 (love). A formal, written-style expression.

Examples

皆様の今後のご活躍を願ってやみません。 I sincerely wish for everyone's continued success.
彼は故郷の自然をこよなく愛してやまなかった。 He loved the nature of his hometown dearly and without end.
二度とこのような事故が起きないことを祈って止みません。 I earnestly pray that such an accident will never happen again.