Is the Golden Rule found in Islam?

NO.

Howard Kainz writes, " The Golden Rule, in its negative or positive formulations, is incorporated not only in Christianity (Matt. 7:12), where Jesus declares it is a summary of “the law and the prophets,” but also in other major religions. For example, in Judaism, “What is hateful to you, do not do to your neighbor”; in Hinduism, “Let no man do to another that which would be repugnant to himself”’; in Buddhism, “Hurt not others in ways that you yourself would find hurtful”; in Confucianism, “What you do not want done to yourself, do not do unto others.”

I took this as evidence of the relative universality of rational ethical principles in the world. But in Islam, I could find nothing of the sort, rather just the opposite – a reverse Golden Rule, so to speak: “Muhammad is the messenger of Allah. Be merciful to one another, but ruthless to the unbelievers” (Qur’an 48:29); “Never take unbelievers for friends” (3:28). Furthermore, the commands in the Qur’an to slay the unbelievers wherever they find them (2:191), not befriend them (3:28), fight them and show them harshness (9:123), and smite their heads (47:4) – accentuate distance from the Golden Rule."

He goes on in this article to point out that Islam also reverses the last seven Commandments.