Anas (Allah be pleased with him) reported that the Messenger of Allah ﷺ used to observe fast till it was said that he had observed fast, he had observed fast (perhaps never to break it), and he did not fast till it was said that he had given up fast, he had given up fast (perhaps never to observe it).
وَحَدَّثَنِيهِ عَلِيُّ بْنُ حُجْرٍ، حَدَّثَنَا عَلِيُّ بْنُ مُسْهِرٍ، ح وَحَدَّثَنِي إِبْرَاهِيمُ بْنُ مُوسَى، أَخْبَرَنَا عِيسَى بْنُ يُونُسَ، كِلاَهُمَا عَنْ عُثْمَانَ بْنِ حَكِيمٍ، فِي هَذَا الإِسْنَادِ . بِمِثْلِهِ .
Sahih Muslim, 1158
Sahih Muslim, Vol. 3, Book of Fasting, Hadith 2586
Sahih Muslim, Book of Fasting, Hadith 2586