Genesis 4:9

איה הבל אחיך WHERE IS ABEL THY BROTHER — thus entering into a friendly conversation with him: perhaps he might repent and say, “I have killed him, and sinned against You” (Genesis Rabbah 19:11). לא ידעתי I KNOW NOT — He became a deceiver of the Most High (i. e. he persuaded himself that he could deceive Him) (Numbers Rabbah 20:6). השומר אחי אנכי AM I MY BROTHER’S KEEPER — This is a question. Similarly, wherever ‘ה has a חטף פתח it introduces a question.

וַיֹּ֤אמֶר יְהֹוָה֙ אֶל־קַ֔יִן אֵ֖י הֶ֣בֶל אָחִ֑יךָ וַיֹּ֙אמֶר֙ לֹ֣א יָדַ֔עְתִּי הֲשֹׁמֵ֥ר אָחִ֖י אָנֹֽכִי׃

And the Lord said to Qayin, Where is Hevel thy brother? And he said, I know not: am I my brother’s keeper?