Hadithcore
Sunan Abi Dawud, 2424
sahih· Al-Albani

Al-Auza'i said:

I always concealed it, but I found that it became known widely, that is, the tradition on Ibn Busr about fasting on Saturday. Abu Dawud said: Malik said: This is a false (tradition).

حَدَّثَنَا مُحَمَّدُ بْنُ الصَّبَّاحِ بْنِ سُفْيَانَ، حَدَّثَنَا الْوَلِيدُ، عَنِ الأَوْزَاعِيِّ، قَالَ مَا زِلْتُ لَهُ كَاتِمًا حَتَّى رَأَيْتُهُ انْتَشَرَ ‏.‏ يَعْنِي حَدِيثَ عَبْدِ اللَّهِ بْنِ بُسْرٍ هَذَا فِي صَوْمِ يَوْمِ السَّبْتِ ‏.‏ قَالَ أَبُو دَاوُدَ قَالَ مَالِكٌ هَذَا كَذِبٌ ‏.‏

References2 variants
In-Book Reference
Book 14, Hadith 112
English Reference
Book 13, Hadith 2418