Yahya related to me from Malik from Ibn Shihab from Ubaydullah ibn Abdullah ibn Utba ibn Masud from Abdullah ibn Abbas that the Messenger of Allah, (ﷺ), left for Makka in Ramadan during the year of the conquest, and fasted until he reached al-Kadid. He then broke the fast, and so everyone else did so as well. What people used to do was act according to whatever the Messenger of Allah, (ﷺ), had done most recently.

حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ عُتْبَةَ بْنِ مَسْعُودٍ، عَنْ عَبْدِ اللَّهِ بْنِ عَبَّاسٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم خَرَجَ إِلَى مَكَّةَ عَامَ الْفَتْحِ فِي رَمَضَانَ فَصَامَ حَتَّى بَلَغَ الْكَدِيدَ ثُمَّ أَفْطَرَ فَأَفْطَرَ النَّاسُ وَكَانُوا يَأْخُذُونَ بِالأَحْدَثِ فَالأَحْدَثِ مِنْ أَمْرِ رَسُولِ اللَّهِ صلى الله عليه وسلم ‏.‏