。
No news is good news.
Literal
Safely [at-に] letter not-exist.
無事に便りなし — a Japanese proverb meaning 'if they're safe, there'll be no word from them.' In other words, silence suggests all is well. 便り = 'letter, news, word from' (not the direction sense). なし is the classical negative form of ない. Shares the sentiment of English 'no news is good news.'