Fasting on Mondays and Thursdays

 Bismillahirrahmanirrahim

  Peer (monday) aur Jumairat (Thursday ) ko Roza Rakhna Sunnat hai

Hazrat Abu Qatada Ansari radi allahu anhu se rivayat hai ki Rasool-Allah Sallallahu Alalhi wasallam se pucha Peer ke din ( yani monday) ke roze ke bare mein (yani aap us din roza kyun rakhte ho) to Aap Sallalalahu alalhi wasallam ne farmaya ki main us din Paida hua tha aur us din mujh par wahi nazil huyee thi.
Sahih Muslim, Vol 3, 2747

Aisha Radhi allahu anha se rivayat hai ki Rasool-Allah Sal-Allahu alaihi wasallam peer (monday) aur jumairat (Thursday ) ko khas taur se roza rakhte they
Jamia Tirmidhi , Vol 1, 723 - Hasan

Abu hurairah radi allahu anhu se rivayat hai ki Rasool-Allah Sal-Allahu alaihi wasallam ne farmaya peer (monday) aur jumairat (Thursday ) ko bande ke aamal ALLAH ki baargah mein pesh kiye jate hain , aur mujhe ye pasand hai ki mere aamal jab ALLAH ki baargah mein pesh ho to main roze se hu
Jamia Tirmidhi , Vol 1, 725 - Hasan
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*It is sunnah to fasting on Monday and Thursday*

Abu Qatada Ansari (Allah be pleased with him) reported that Allah's Massenger (may peace be upon him) was asked about fasting on monday, whereupon he said: It is (the day) when I was born and revelation was sent down to me.
Sahih Muslim, Book 6, 2606

Umm Aayesha Radhi allahu anhu reports Rasool-Allah Sal-Allahu alaihi wasallam (often) gave importance to the fasting on Mondays and Thursdays...
Jamia Tirmidhi , Book 3, 745-Hasan
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Abu Hurairah Radiallahu anhu reports Rasool-Allah Sal-Allahu alaihi wasallam said: Deeds are presented (in front of Allah subhanahu on Mondays and Thursdays. I desire that my deeds be presented whilst I am fasting.
Jamia Tirmidhi , Book 3, 747-Hasan