Abu Qatadah (May Allah be pleased with him) reported:
The Messenger of Allah (ﷺ) was asked about fasting on Mondays. He said, "That is the day on which I was born and the day on which I received Revelation."[Muslim].
عن أبي قتادة رضي الله عنه أن رسول الله صلى الله عليه وسلم: سئل عن صوم يوم الاثنين فقال:
"ذلك يوم ولدت فيه، ويوم بعثت أو أنزل علي فيه"
((رواه مسلم)).