بسم الله الرحمن الرحيم

عن عائشة قالت كان نبي صلى الله عليه وسلم يتحرى صوم الاثنين والخميس
‘Aa’ishah (may Allaah be pleased with her) said: The Prophet (peace and blessings of Allaah be upon him) was keen to fast on Mondays and Thursdays.
At-Tirmidhee 745. Declared Saheeh by Shaykh Al-Albanee.
عن أبي هريرة أن رسول الله صلى الله عليه وسلم قال تعرض الأعمال يوم الثنين والخميس فأحب أن يعرض عملي وأنا صائم
Abu Hurayrah (may Allaah be pleased with him) that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “The deeds are presented (to Allaah) on Mondays and Thursdays, so I love that my deeds are presented while I am fasting.”
At-Tirmidhee 747. Declared Saheeh by Shaykh Al-Albanee.
أن رسول الله صلى الله عليه وسلم سئل عن صومه الاثنين؟ قال دلك يومن ولدت فيه ويوم بعثت – أو أنزل علي – فيه
the Messenger of Allaah (peace and blessings of Allaah be upon him) was asked about fasting on Mondays, and he said: “That is the day on which I was born and the day on which I was sent – or on which the Revelation came to me.”
Saheeh Muslim 1162.
عَنْ حَفْصَةَ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَصُومُ ثَلاَثَةَ أَيَّامٍ مِنَ الشَّهْرِ الاِثْنَيْنِ وَالْخَمِيسِ وَالاِثْنَيْنِ مِنَ الْجُمُعَةِ الأُخْرَى
Narrated Hafsah, Ummul Mu’minin: The apostle of Allah (ﷺ) used to fast three days every month: Monday, Thursday and Monday in the next week.
Sunan Abu Dawood 2451. Declared Hasan by Shaykh Al-Albanee