Is it obligatory to ask the people of knowledge when there is ambiguity in a legal ruling, or is it sufficient to act upon what is more cautious?

Precaution is good and clears one's conscience. Leaving what is doubtful for what is not doubtful is a way of avoiding suspicions. It is not permissible to look into someone's private papers if they explicitly or implicitly forbid it. However, it is permissible to look into them with their explicit or implicit permission. The early Muslims (Salaf) disliked looking into another person's book without their permission. The hadith "Whoever looks into his brother's book without his permission is as if he is looking into fire" has been interpreted as referring to a book containing secrets and trusts, or to any book in general.