“Do not fast on Saturdays apart from days when you are obliged to fast. If anyone of you cannot find anything other than grape stalks or the bark of a tree, let him suck on it.” Another chain from 'Abdullah bin Busr, from his sister who said: "The Messenger of Allah ﷺ said," and he mentioned similarly.
قَالَ رَسُولُ اللَّهِ ﷺ لاَ تَصُومُوا يَوْمَ السَّبْتِ إِلاَّ فِيمَا افْتُرِضَ عَلَيْكُمْ فَإِنْ لَمْ يَجِدْ أَحَدُكُمْ إِلاَّ عُودَ عِنَبٍ أَوْ لِحَاءَ شَجَرَةٍ فَلْيَمُصَّهُ حَدَّثَنَا حُمَيْدُ بْنُ مَسْعَدَةَ حَدَّثَنَا سُفْيَانُ بْنُ حَبِيبٍ عَنْ ثَوْرِ بْنِ يَزِيدَ عَنْ خَالِدِ بْنِ مَعْدَانَ عَنْ عَبْدِ اللَّهِ بْنِ بُسْرٍ عَنْ أُخْتِهِ قَالَتْ قَالَ رَسُولُ اللَّهِ ﷺ فَذَكَرَ نَحْوَهُ