Reference: http://mufti.af.org.sa/ar/content/حكم-من-سئل-عن-شيء-يعلمه-ولم-يجب-عليه
Question: If I am asked about something I know about, and I don’t want to disclose it, will I be sinful if I said “I don’t know”?
Response: If you are asked about something you know about, and you don’t want to say anything about it, then respond in an ambiguous manner so as not to lie. And if the matter which you are asked about is of benefit to the questioner, or will prevent any harm befalling him, then you should tell him what you know.
