Ya-Sin 36:11

Innama tunthiru mani ittabaAAaaththikra wakhashiya arrahmanabilghaybi fabashshirhu bimaghfiratin waajrin kareem

You can only warn one who follows the message and fears the Most Merciful unseen. So give him good tidings of forgiveness and noble reward.

You can (usefully) warn only the one who follows the advice and fears the RaHmān (the All-Merciful Allah) without seeing (Him). So give him the good news of forgiveness and of a noble reward.