The Book of Fasting
وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَأَبُو كُرَيْبٍ قَالاَ حَدَّثَنَا ابْنُ نُمَيْرٍ، وَقَالَ أَبُو بَكْرٍ، حَدَّثَنَا عَبْدُ الرَّحِيمِ بْنُ سُلَيْمَانَ، كِلاَهُمَا عَنْ هِشَامٍ، بِهَذَا الإِسْنَادِ أَنَّ حَمْزَةَ، قَالَ إِنِّي رَجُلٌ أَصُومُ أَفَأَصُومُ فِي السَّفَرِThis hadith has been narrated on the authority of Hisham with the same chain of transmitters that Hamza said:I am a person much used to fasting. Should I fast during the journey? (The rest of the hadith is the same)
From Sahih Muslim, whose reports the scholars accept as authentic.