Reward for fasting is up to Allah for the servant restrains himself from his bodily desires

Messenger of Allah ﷺ said, "Fasting is a shield (or a screen or a shelter). So, the person observing fasting should avoid sexual relation with his wife and should not behave foolishly and impudently, and if somebody fights with him or abuses him, he should tell him twice, 'I am fasting."

The Prophet ﷺ added, "By Him in Whose Hands my soul is, the smell coming out from the mouth of a fasting person is better in the sight of Allah than the smell of musk. (Allah says about the fasting person), 'He has left his food, drink and desires for My sake. The fast is for Me. So I will reward (the fasting person) for it and the reward of good deeds is multiplied ten times."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ: «الصِّيَامُ جُنَّةٌ: فَلاَ يَرْفُثْ، وَلاَ يَجْهَلْ؛ وَإِنِ امْرُؤٌ قَاتَلَهُ أَوْ شَاتَمَهُ فَلْيَقُلْ: إِنِّي صَائِمٌ مَرَّتَيْنِ۔»

«وَالَّذِي نَفْسِي بِيَدِهِ لَخُلُوفُ فَمِ الصَّائِمِ أَطْيَبُ عِنْدَ اللَّهِ تَعَالَى مِنْ رِيحِ الْمِسْكِ: يَتْرُكُ طَعَامَهُ، وَشَرَابَهُ، وَشَهْوَتَهُ مِنْ أَجْلِي؛ الصِّيَامُ لِي وَأَنَا أَجْزِي بِهِ وَالْحَسَنَةُ بِعَشْرِ أَمْثَالِهَا۔»  

The Prophet ﷺ said, "Allah said: The Fast is for Me and I will give the reward for it, as he (the one who observes the fast) leaves his sexual desire, food and drink for My Sake. Fasting is a screen (from Hell) and there are two pleasures for a fasting person, one at the time of breaking his fast, and the other at the time when he will meet his Lord. And the smell of the mouth of a fasting person is better in Allah's Sight than the smell of musk." (See Hadith No. 128, Vol. 3).  

عَنِ النَّبِيِّ ﷺ قَالَ يَقُولُ اللَّهُ ﷻ الصَّوْمُ لِي وَأَنَا أَجْزِي بِهِ يَدَعُ شَهْوَتَهُ وَأَكْلَهُ وَشُرْبَهُ مِنْ أَجْلِي وَالصَّوْمُ جُنَّةٌ وَلِلصَّائِمِ فَرْحَتَانِ فَرْحَةٌ حِينَ يُفْطِرُ وَفَرْحَةٌ حِينَ يَلْقَى رَبَّهُ وَلَخَلُوفُ فَمِ الصَّائِمِ أَطْيَبُ عِنْدَ اللَّهِ مِنْ رِيحِ الْمِسْكِ  

[Machine] The Prophet ﷺ said: "The breath of the fasting person is more pleasant to Allah than the scent of musk." He said: "Your Lord said: 'My servant has left his desire, food, and drink for My sake. The fasting is for Me and I will reward him for it.'"  

عَنِ النَّبِيِّ ﷺ قَالَ لَخُلُوفُ فَمِ الصَّائِمِ أَطْيَبُ عِنْدَ اللهِ مِنْ رِيحِ الْمِسْكِ قَالَ قَالَ رَبُّكُمْ ﷻ عَبْدِي تَرَكَ شَهْوَتَهُ وَطَعَامَهُ وَشَرَابَهُ ابْتِغَاءَ مَرْضَاتِي وَالصَّوْمُ لِي وَأَنَاأَجْزِي بِهِ  

[Machine] The Messenger of Allah ﷺ said, "By the One in whose hand is my soul, the scent of the fasting person's mouth is more pleasant to Allah than the scent of musk. He says, 'The fasting person abstains from their desires, food, and drink for My sake. Fasting is for Me and I will reward it accordingly, with every good deed being multiplied ten times to seven hundred times, except for fasting, which is for Me and I will reward it.'"  

أَنَّ رَسُولَ اللهِ ﷺ قَالَ وَالَّذِي نَفْسِي بِيَدِهِ لَخُلُوفُ فَمِ الصَّائِمِ أَطْيَبُ عِنْدَ اللهِ مِنْ رِيحِ الْمِسْكِ يَقُولُ ﷻ إِنَّمَا يَذَرُ شَهْوَتَهُ وَطَعَامَهُ وَشَرَابَهُ مِنْ أَجْلِي فَالصَّوْمُ لِي وَأَنَا أَجْزِي بِهِ كُلُّ حَسَنَةٍ بِعَشْرِ أَمْثَالِهَا إِلَى سَبْعِ مِائَةِ ضِعْفٍ إِلَّا الصِّيَامَ فَهُوَ لِي وَأَنَا أَجْزِي بِهِ  

[Machine] And the Messenger of Allah ﷺ said, "By the One in whose hand is the soul of Muhammad, the breath of the fasting person is sweeter to Allah than the fragrance of musk. The fasting person abstains from their desires, food, and drink for My sake, and I will reward them for it."  

وَقَالَ رَسُولُ اللهِ ﷺ وَالَّذِي نَفْسُ مُحَمَّدٍ بِيَدِهِ لَخُلُوفُ فَمِ الصَّائِمِ أَطْيَبُ عِنْدَ اللهِ مِنْ رِيحِ الْمِسْكِ يَذَرُ شَهْوَتَهُ وَطَعَامَهُ وَشَرَابَهُ مِنْ جَرَّايَ فَالصِّيَامُ لِي وَأَنَا أَجْزِي بِهِ  

[Machine] "On the authority of the Prophet of Allah ﷺ , he said, 'The smell of the breath of a fasting person is more pleasing to Allah than the scent of musk.' He said, 'This person has fasted for my sake and has abandoned his desires for food and drink for my sake. The fasting is for me and I shall reward it.'"  

عَنْ نَبِيِّ اللهِ ﷺ أَنَّهُ قَالَ لَخُلُوفُ فَمِ الصَّائِمِ أَطْيَبُ عِنْدَ اللهِ مِنْ فَيْحِ الْمِسْكِ قَالَ صَامَ هَذَا مِنْ أَجْلِي وَتَرَكَ شَهْوَتَهُ عَنِ الطَّعَامِ وَالشَّرَابِ مِنْ أَجْلِي فَالصَّوْمُ لِي وَأَنَا أَجْزِي بِهِ  

"قَال اللهُ -تَعَالى-: الصَّومُ جُنَّةٌ يُجَنُّ بِهَا عَبْدِي مِن النَّارِ, وَالصَّومُ لِي وَأَنَا أَجْزِي به، يَدعُ طَعَامَهُ وَشَهْوتَهُ مِن أَجْلِي، وَالَّذي نَفْسِي بِيَده لَخلُوفُ فَمِ الصَّائِم عِنْدَ اللهِ يَوْمَ الْقِيَامَةِ أَطيَبُ مِن رِيحِ الْمِسْكِ".  

"قَال رَبُّكْمُ: الصَّوْمُ جُنَّةٌ مِنَ النَّارِ، وَلِى الصَّوْمُ وَأنَا أجْزِى به يَدَعُ شَهْوَتَه وَطَعَامَهُ وَشَرَابَهُ مِنْ أجْلِى، لَخَلُوفُ فمِ الصائِم أطيَبُ عنْدَ اللهِ مِن ريح الْمِسْكِ".