Not "You must kill unbelievers in Mecca," but you can, you are allowed to, but only after a grace period is over and only if there's no other pact in place and only if they try to stop you getting to the Kaaba, and only if they attack you first.
「不信心者はメッカで殺せ」ではなく 殺すことが許されるのは それは猶予期間が切れた場合のみで しかも他に何の約束事もなく そしてカアバ聖殿への道を阻まれ 攻撃を仕掛けられた場合に限ります