Abū al-ʿAbbās Muḥammad b. Yaʿqūb > al-ʿAbbās b. al-Walīd b. Mazyad al-Bayrūtī > al-Awzāʿī > Yaḥyá b. Abū Kathīr > Abū Qilābah > Abū Asmāʾ > Thawbān

I went out with the Messenger of Allah ﷺ for eighteen nights of Ramadan. When we were in al-Baqi', the Messenger of Allah ﷺ saw a man performing Halq(Removing some or all of the hair on the head) and he said, "The one doing Halq and the one performing Taqsir (trimming the hair but not shaving it completely) have broken their fast." Al-Awza'i established this chain of narration, verified and clarified the hearing of each narrator from their respective sources. Shayban ibn Abdur Rahman an-Nahwi and Hisham ibn Abi Abdullah ad-Dastuwai followed him in that. All of them are trustworthy narrators. So, this hadith is authentic according to the criteria of the two Shaykhs (Imams Bukhari and Muslim), and they did not exclude it.

حَدَّثَنَا أَبُو الْعَبَّاسِ مُحَمَّدُ بْنُ يَعْقُوبَ ثنا الْعَبَّاسُ بْنُ الْوَلِيدِ بْنِ مَزْيَدٍ الْبَيْرُوتِيُّ ثنا الْأَوْزَاعِيُّ حَدَّثَنِي يَحْيَى بْنُ أَبِي كَثِيرٍ حَدَّثَنِي أَبُو قِلَابَةَ حَدَّثَنِي أَبُو أَسْمَاءَ حَدَّثَنِي ثَوْبَانُ قَالَ

خَرَجْتُ مَعَ رَسُولِ اللَّهِ ﷺ لِثَمَانِيَ عَشْرَةَ لَيْلَةً خَلَتْ مِنْ شَهْرِ رَمَضَانَ فَلَمَّا كَانَ بِالْبَقِيعِ نَظَرَ رَسُولُ اللَّهِ ﷺ إِلَى رَجُلٍ يَحْتَجِمُ فَقَالَ رَسُولُ اللَّهِ ﷺ «أَفْطَرَ الْحَاجِمُ وَالْمَحْجُومُ» قَدْ أَقَامَ الْأَوْزَاعِيُّ هَذَا الْإِسْنَادُ فَجَوَّدَهُ وَبَيَّنَ سَمَاعَ كُلِّ وَاحِدٍ مِنَ الرُّوَاةِ مِنْ صَاحِبِهِ «وَتَابَعَهُ عَلَى ذَلِكَ شَيْبَانُ بْنُ عَبْدِ الرَّحْمَنِ النَّحْوِيُّ وَهِشَامُ بْنُ أَبِي عَبْدِ اللَّهِ الدَّسْتُوَائِيُّ وَكُلُّهُمْ ثِقَاتٌ» فَإِذَا الْحَدِيثُ صَحِيحٌ عَلَى شَرْطِ الشَّيْخَيْنِ وَلَمْ يُخَرِّجَاهُ