Do you testify on behalf of a non-Muslim against a Jew?

Originally, rendering testimony is a communal obligation (fard kifaya), but it becomes an individual obligation (wajib) if the witness is summoned to do so, or if withholding testimony would lead to the loss of rights for an oppressed person. Allah Almighty says: (And let not the witnesses refuse when they are called upon) and (And do not conceal testimony, for whoever conceals it - his heart is indeed sinful). It is obligatory for the witness to render testimony whether the person testified for or against is a Muslim or a non-Muslim, and whether they are a relative or a stranger; their religion has no bearing on the testimony. However, it is not permissible to swear by other than Allah when rendering testimony. It is permissible not to give testimony if it will result in harm to the witness, as Allah Almighty says: (And let no scribe be harmed or any witness).