﴿ وَأَصْبَحَ فُؤَادُ أُمِّ مُوسَىٰ فَٰرِغًا ۖ إِن كَادَتْ لَتُبْدِى بِهِۦ لَوْلَآ أَن رَّبَطْنَا عَلَىٰ قَلْبِهَا لِتَكُونَ مِنَ ٱلْمُؤْمِنِينَ ﴾

“On the morrow, however, an aching void grew up in the heart of the mother of Moses, and she would indeed have disclosed all about him had We not endowed her heart with enough strength to keep alive her faith [in Our promise].”

(And the heart of the mother of Moses) Jochabed (became void) from the preoccupation or mention of anything other than Moses, (and she would have betrayed him) by admitting that Moses was her son after being adopted by Pharaoh (if We had not fortified her heart) with patience, (that she might be of the believers) in the promise of Allah that he will be one of the messengers.