Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
nasai-kubra:2774 – ʿAlī b. Khashram > ʿĪsá > Thawr > Khālid b. Maʿdān > ʿAbdullāh b. Busr

[Machine] The Messenger of Allah ﷺ said, "Do not fast on Saturdays except what is obligatory upon you."  

الكبرى للنسائي:٢٧٧٤ – أَخْبَرَنَا عَلِيُّ بْنُ خَشْرَمٍ قَالَ أَخْبَرَنَا عِيسَى عَنْ ثَوْرٍ عَنْ خَالِدِ بْنِ مَعْدَانَ عَنْ عَبْدِ اللهِ بْنِ بُسْرٍ قَالَ

قَالَ رَسُولُ اللهِ ﷺ «لَا تَصُومُوا يَوْمَ السَّبْتِ إِلَّا فِيمَا افْتُرِضَ عَلَيْكُمْ»  

See similar narrations below:

Collected by Ṭabarānī
tabarani:21288 – Mūsá b. ʿĪsá b. al-Mundhir al-Ḥimṣī from my father > Muḥammad b. Ḥarb > al-Zubaydī > Fuḍayl b. Faḍālah > ʿAbdullāh b. Busr > Khālatih

[Machine] "I heard the Messenger of Allah ﷺ saying, 'Do not fast on Saturdays unless it is an obligatory fast prescribed by Allah upon you.'"  

الطبراني:٢١٢٨٨ – حَدَّثَنَا مُوسَى بْنُ عِيسَى بْنِ الْمُنْذِرِ الْحِمْصِيُّ ثنا أَبِي ثنا مُحَمَّدُ بْنُ حَرْبٍ عَنِ الزُّبَيْدِيِّ عَنْ فُضَيْلِ بْنِ فَضَالَةَ عَنْ عَبْدِ اللهِ بْنِ بُسْرٍ عَنْ خَالَتِهِ قَالَتْ

سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ «لَا تَصُومُوا يَوْمَ السَّبْتِ إِلَّا فِيمَا افْتَرَضَ اللهُ عَلَيْكُمْ»