When Musa's mother became so worried and confused, it was inspired into her heart and mind what she should do, as Allah says:

﴿وَأَوْحَيْنَآ إِلَى أُمِّ مُوسَى أَنْ أَرْضِعِيهِ فَإِذَا خِفْتِ عَلَيْهِ فَأَلْقِيهِ فِى اليَمِّ وَلاَ تَخَافِى وَلاَ تَحْزَنِى إِنَّا رَآدُّوهُ إِلَيْكِ وَجَـعِلُوهُ مِنَ الْمُرْسَلِينَ ﴾

(And We inspired the mother of Musa (telling): "Suckle him, but when you fear for him, then cast him into the river and fear not, nor grieve. Verily, We shall bring him back to you, and shall make him one of (Our) Messengers.'') Her house was on the banks of the Nile, so she took a box and made it into a cradle, and started to nurse her child. When someone came to her that she was afraid of, she would go and put him in that box and put it in the river, and she would tie it with a rope. One day someone that she was afraid of came to the house, so she went and put the child in that box and put it in the river, but she forgot to tie it. The water carried him away, past the house of Fir`awn, where some servant women picked the box up and took it to Fir`awn's wife. They did not know what was inside, and they were afraid that they would be in trouble if they opened it without her. When the box was opened, they saw it was a child with the most beautiful features. Allah filled her heart with love for him when she saw him; this was because she was blessed and because Allah wanted to honor her and cause her husband's doom. Allah says:

﴿فَالْتَقَطَهُ ءَالُ فِرْعَوْنَ لِيَكُونَ لَهُمْ عَدُوّاً وَحَزَناً﴾

(Then the household of Fir`awn picked him up, that he might become for them an enemy and a (cause of) grief.) Allah says:

﴿إِنَّ فِرْعَوْنَ وَهَـمَـنَ وَجُنُودَهُمَا كَانُواْ خَـطِئِينَ﴾

(Verily, Fir`awn, Haman and their armies were sinners.)

﴿وَقَالَتِ امْرَأَتُ فِرْعَوْنَ قُرَّةُ عَيْنٍ لِّى وَلَكَ﴾

(And the wife of Fir`awn said: "A comfort of the eye for me and for you...'') means, when Fir`awn saw him, he wanted to kill him, fearing that he was one of the Children of Israel. But his wife Asiyah bint Muzahim came to the child's defence and tried to endear him to Fir`awn, saying,

﴿قُرَّةُ عَيْنٍ لِّى وَلَكَ﴾

(A comfort of the eye for me and for you.) Fir`awn said: "For you he may be, but not for me. And this was indeed the case: Allah guided her because of him, and destroyed him at his hands.

﴿عَسَى أَن يَنفَعَنَآ﴾

(perhaps he may be of benefit to us,) This is indeed what happened in her case, for Allah guided her through him and caused her to dwell in Paradise because of him.

﴿أَوْ نَتَّخِذَهُ وَلَدًا﴾

(or we may adopt him as a son.) She wanted to take him and adopt him as a son, because she had no children from Fir`awn.

﴿وَهُمْ لاَ يَشْعُرُونَ﴾

(And they perceived not.) means, they did not know what Allah planned for them when they picked him up, by His great wisdom and definitive proof.

﴿وَأَصْبَحَ فُؤَادُ أُمِّ مُوسَى فَارِغاً إِن كَادَتْ لَتُبْدِى بِهِ لَوْلا أَن رَّبَطْنَا عَلَى قَلْبِهَا لِتَكُونَ مِنَ الْمُؤْمِنِينَ - وَقَالَتْ لأُخْتِهِ قُصِّيهِ فَبَصُرَتْ بِهِ عَن جُنُبٍ وَهُمْ لاَ يَشْعُرُونَ - وَحَرَّمْنَا عَلَيْهِ الْمَرَاضِعَ مِن قَبْلُ فَقَالَتْ هَلْ أَدُلُّكُمْ عَلَى أَهْلِ بَيْتٍ يَكْفُلُونَهُ لَكُمْ وَهُمْ لَهُ نَـصِحُونَ - فَرَدَدْنَـهُ إِلَى أُمِّهِ كَىْ تَقَرَّ عَيْنُهَا وَلاَ تَحْزَنَ وَلِتَعْلَمَ أَنَّ وَعْدَ اللَّهِ حَقٌّ وَلَـكِنَّ أَكْثَرَهُمْ لاَ يَعْلَمُونَ ﴾

(10. And the heart of the mother of Musa became empty. She was very near to disclose his (case), had We not strengthened her heart, so that she might remain as one of the believers.) (11. And she said to his sister: "Follow him.'' So she watched him from a far place (secretly), while they perceived not.) (12. And We had already forbidden foster suckling mothers for him, until she said: "Shall I direct you to a household who will rear him for you, and look after him in a good manner'') (13. So We restored him to his mother, that her eye might be comforted, and that she might not grieve, and that she might know that the promise of Allah is true. But most of them know not.)