「」。
My sister didn't say 'hello.'
Literal
Younger-sister [topic-は] 'hello' [quotative-とは] said not.
「こんにちは」とは言わなかった — the quotative とは here carries a nuance of contrast or emphasis: 'she didn't say (even) hello.' The は after と adds the contrastive weight — implying she might have said something else, or that hello specifically was expected but omitted.