The Messenger of Allah ﷺ said, "There are no days in this world during which worship is more beloved to Allah, glorified is He, than the ten days. Fasting one day of them is equivalent to fasting an entire year, and one night of them is equivalent to Laylat al-Qadr."
حدثنا عمر بن شبة بن عبيدة حدثنا مسعود بن واصل عن النهاس بن قهم عن قتادة عن سعيد بن المسيب
قال رسول الله ﷺ ما من أيام الدنيا أيام أحب إلى الله سبحانه أن يتعبد له فيها من أيام العشر وإن صيام يوم فيها ليعدل صيام سنة وليلة فيها بليلة القدر
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[Its chain of transmission is daif] Recorded by Tirmidhi, Fasting, chapter on what has been mentioned about deeds during the ten days, no. 758, from the hadith of Masud through this route, and he said it is gharib. See also no. 1382 for its defect.