What is the ruling on one who witnesses a theft but does not report it?

The Shariah encourages concealment, and whoever conceals a Muslim will be concealed by Allah on the Day of Judgment. Therefore, if the stolen item can be recovered without exposing the thief, that is preferable. Otherwise, the owner of the property or their representative must be informed. If not, the informer incurs sin for their negligence in recovering the property, and they are liable for the stolen item in the view of those who consider the omission an act.