Narrated Abu Sa'id al-Khudri: The Messenger of Allah (ﷺ) as saying: Do not observe perpetual fasting. If any of you wants to observe perpetual fast, he should observe it until the dawn. They (the people) asked: You observe perpetual fast ? He replied: My position is not like that of yours. There is One Who gives me to eat, and there is One who gives me to drink.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، أَنَّ بَكْرَ بْنَ مُضَرَ، حَدَّثَهُمْ عَنِ ابْنِ الْهَادِ، عَنْ عَبْدِ اللَّهِ بْنِ خَبَّابٍ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، أَنَّهُ سَمِعَ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ " لاَ تُوَاصِلُوا فَأَيُّكُمْ أَرَادَ أَنْ يُوَاصِلَ فَلْيُوَاصِلْ حَتَّى السَّحَرِ " . قَالُوا فَإِنَّكَ تُوَاصِلُ . قَالَ " إِنِّي لَسْتُ كَهَيْئَتِكُمْ إِنَّ لِي مُطْعِمًا يُطْعِمُنِي وَسَاقِيًا يَسْقِينِي " .
sunnah.com