﴿ 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.”

Then he conceived he kept secret in himself a fear of them. They said ‘Do not be afraid!’ we are messengers from your Lord. And they gave him good tidings of the birth of a knowledgeable boy one endowed with much knowledge and this was Isaac as mentioned in sūrat Hūd Q. 1171.