فَرَدَدۡنَٰهُ إِلَىٰٓ أُمِّهِۦ كَيۡ تَقَرَّ عَيۡنُهَا وَلَا تَحۡزَنَ وَلِتَعۡلَمَ أَنَّ وَعۡدَ ٱللَّهِ حَقّٞ وَلَٰكِنَّ أَكۡثَرَهُمۡ لَا يَعۡلَمُونَ ١٣
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.
Translation: Saheeh International (English)
Each word's meaning and sound
So we returned Moses to his mother, for her eyes, after seeing what they longed for, called become joyful and rest, so that she would not be grieved by separation from him, and that she would realise the promise of Allah to return him to her to have been undoubtedly true. However, many people were unaware of this promise; no one knew she was his mother.
Al-Mukhtasar in interpreting the Noble Quran