Sunan an-Nasa'i 2186
سنن النسائي#2186Sahihأَخْبَرَنِي عَمْرُو بْنُ عُثْمَانَ، عَنْ بَقِيَّةَ، قَالَ حَدَّثَنَا بَحِيرٌ، عَنْ خَالِدٍ، عَنْ جُبَيْرِ بْنِ نُفَيْرٍ، أَنَّ رَجُلاً، سَأَلَ عَائِشَةَ عَنِ الصِّيَامِ، فَقَالَتْ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يَصُومُ شَعْبَانَ كُلَّهُ وَيَتَحَرَّى صِيَامَ الاِثْنَيْنِ وَالْخَمِيسِ .
It was narrated from Jubair bin Nufair that a man asked Aishah about fasting and she said:"The Messenger of Allah used to fast all of Shaban, and he made sure to fast on Mondays and Thursdays
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 22:97