فَرَدَدْنَـٰهُ إِلَىٰٓ أُمِّهِۦ كَىْ تَقَرَّ عَيْنُهَا وَلَا تَحْزَنَ وَلِتَعْلَمَ أَنَّ وَعْدَ ٱللَّهِ حَقٌّ وَلَـٰكِنَّ أَكْثَرَهُمْ لَا يَعْلَمُونَ
So We restored him to his mother that she might be content and not grieve and that she would know that the promise of Allāh is true. But most of them [i.e., the people] do not know.
Dimensional Analysis
Context
And we ordained that he refused suck at first, until (His sister came up and) said: "Shall I point out to you the people of a house that will nourish and bring him up for you and be sincerely attached to him?"...
Thus did We restore him to his mother, that her eye might be comforted, that she might not grieve, and that she might know that the promise of Allah is true: but most of them do not understand.
When he reached full age, and was firmly established (in life), We bestowed on him wisdom and knowledge: for thus do We reward those who do good.
Related Verses
واللهُ أعلمُ بالصَّواب