[Machine] The Messenger of Allah ﷺ said, "Do not fast on the day of Saturday. And if any of you cannot find anything to eat except the bark of a tree, then let him chew it." This is narrated in the hadith of Ad-Daqqaq, and in the narration of Ibn 'Abdan, it is mentioned, "None of you should fast on the day of Saturday except for what is obligatory upon him. And if he cannot find anything to eat except for the bark of a tree, then let him chew it." This is also narrated by Al-Walid ibn Muslim and others from Thawr.  

قَالَ رَسُولُ اللهِ ﷺ لَا تَصُومُوا يَوْمَ السَّبْتِ وَإِنْ لَمْ يَجِدْ أَحَدُكُمْ إِلَّا عُودًا فَلْيَمْضُغْهُ لَفْظُ حَدِيثِ الدَّقَّاقِ وَفِي رِوَايَةِ ابْنِ عَبْدَانَ لَا يَصُومَنَّ أَحَدُكُمْ يَوْمَ السَّبْتِ إِلَّا فِيمَا افْتُرِضَ عَلَيْهِ وَإِنْ لَمْ يَجِدْ إِلَّا لِحَاءَ شَجَرَةٍ فَلْيَمْضُغْهُ وَرَوَاهُ أَيْضًا الْوَلِيدُ بْنُ مُسْلِمٍ وَغَيْرُهُ عَنْ ثَوْرٍ