Surah Az-Zukhruf, Verse 89

فَٱصۡفَحۡ عَنۡهُمۡ وَقُلۡ سَلَٰمٞۚ فَسَوۡفَ يَعۡلَمُونَ٨٩

fa-iṣ'faḥ ʿanhum waqul salāmun fasawfa yaʿlamūna

So turn aside from them and say, "Peace." But they are going to know.