ON THE SUBJECT OF 229 VIRTUES OF FASTING ON MONDAYS AND THURSDAYS ; FASTING MONDAY H 1281 "The Messenger of Allah, praise and peace be upon him, was asked about fasting on Monday and replied, 'That is the day upon which I was born and the day upon which I was sent or it was sent down upon me (meaning Gabriel with the Koran).'" R 1281 Muslim with a chain up to Abu Katadah who related that the Messenger of Allah, praise and peace be upon him, said this.
باب استحباب صوم الإثنين والخميس 1255- عن أَبي قتادة رضي الله عنه : أنَّ رسول الله صلى الله عليه وآله وسلم سُئِلَ عَنْ صَومِ يَوْمِ الإثْنَيْنِ ، فَقَالَ : "ذَلِكَ يَومٌ وُلِدْتُ فِيهِ ، وَيَومٌ بُعِثْتُ ، أَوْ أُنْزِلَ عَلَيَّ فِيهِ" رواه مسلم .