Hadithcore
Sahih Muslim, 1113 c
sahih

It has been narrated on the authority of Zuhri with the same chain of transmitters that breaking of fast (in a journey) is the final of the two commands (whether one may fast or one may break it), and it is the last command of the Messenger of Allah (ﷺ) which is to be accepted as final. Zuhri said:

The Messenger of Allah (ﷺ) marched on Mecca on the morning of 14th of Ramadan (lit. when thirteen nights had passed).

حَدَّثَنِي مُحَمَّدُ بْنُ رَافِعٍ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، بِهَذَا الإِسْنَادِ قَالَ الزُّهْرِيُّ وَكَانَ الْفِطْرُ آخِرَ الأَمْرَيْنِ وَإِنَّمَا يُؤْخَذُ مِنْ أَمْرِ رَسُولِ اللَّهِ صلى الله عليه وسلم بِالآخِرِ فَالآخِرِ ‏.‏ قَالَ الزُّهْرِيُّ فَصَبَّحَ رَسُولُ اللَّهِ صلى الله عليه وسلم مَكَّةَ لِثَلاَثَ عَشْرَةَ لَيْلَةً خَلَتْ مِنْ رَمَضَانَ ‏.‏

References2 variants
In-Book Reference
Book 13, Hadith 112
USC-MSA web (English) reference
Book 6, Hadith 2468 (deprecated numbering scheme)