﴿ فَأَوْجَسَ مِنْهُمْ خِيفَةًۭ ۖ قَالُوا۟ لَا تَخَفْ ۖ وَبَشَّرُوهُ بِغُلَٰمٍ عَلِيمٍۢ ﴾

“[And when he saw that the guests would not eat,] he became apprehensive of them; [but] they said, “Fear not” - and gave him the glad tiding of [the birth of] a son who would be endowed with deep knowledge.”

Please check ayah 51:30 for complete tafsir.