Surah Al-Qasas 28:10

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

And the heart of Moses' mother became empty [of all else]. She was about to disclose [the matter concerning] him had We not bound fast her heart that she would be of the believers.

Translation: Saheeh International

Tafsir

And the heart of Moses’s mother when she found out that they had picked him up became empty of everything other than him. Indeed in softened from the hardened form its subject omitted in other words understand it as innaha she was about to expose him that is as being her son had We not fortified her heart with …

Excerpt from Tafsir al-Jalalayn, commentary on 28:10, via Quran.com. The reader has the full commentary and 9 more tafsirs.