Dua 40 Allah grants His obedient servants everything they ask for.
(Surah Al-A'raf (07), Verse 156)

وَٱكْتُبْ لَنَا فِى هَـٰذِهِ ٱلدُّنْيَا حَسَنَةً وَفِى ٱلْـَٔاخِرَةِ إِنَّا هُدْنَآ إِلَيْكَ

Waktub lanaa fee haazi hid dunyaa hasanatanw wa fil Aakhirati innnaa hudnaaa ilaik.

And appoint goodness for us in this world and the Hereafter, for indeed we have come back to You.

(Surah Al-A'raf (07), Verse 156)

This supplication is connected to the previous one, which Prophet Musa (A.S.) made for his faith - so that Allah would grant him and his followers goodness in both this world and the Hereafter.
Allah loves His righteous servants more than parents love their child. Even when they ask for something, He does not grant it if it is not suitable or beneficial for them.
A child may stubbornly demand certain foods or drinks, but the parents know it would be harmful. Therefore, they refuse to give it.