Is an action not felt by its intended subject to be considered backbiting if another person perceives it as an insult?

Gheebah (backbiting) is to mention your Muslim brother with what he dislikes, as it is stated in Sahih Muslim. If what is said about him is true, then it is gheebah. If it is not true, then it is buhtan (slander). It is better to respond to ill-treatment with forgiveness, as it is closer to piety, as Allah Almighty says: "And that you pardon is nearer to piety." Insulting a Muslim, or cursing him, or frightening him is unlawful, unless it is for a legitimate Shari'ah right.