Am I sinful if I ask about the ruling on something—whether forbidden or permissible—and someone else acts upon it, even though my intention was merely to ask?

There is no sin upon you for asking if you intend to benefit people by clarifying the ruling of Islamic law for them; rather, you will be rewarded for it. Learning knowledge and asking about what one does not know is obligatory, due to the Almighty’s saying: ﴿So ask the people of the message if you do not know﴾ [An-Nahl: 43], and the Prophet, peace and blessings be upon him, said: "Why did they not ask when they did not know? Indeed, the cure for ignorance is asking." It is obligatory to block the doors of doubts and satanic delusions that prevent you from seeking knowledge.