The Prophet ﷺ said, "There are no days more beloved to Allah in which He is worshipped than the ten days of Dhu al-Hijjah. Fasting one of these days is equivalent to fasting an entire year, and standing in prayer one of its nights is equivalent to standing in prayer on Laylat al-Qadr."
حدثنا أبو بكر بن نافع البصري حدثنا مسعود بن واصل عن نهاس بن قهم عن قتادة عن سعيد بن المسيب
عن النبي ﷺ قال ما من أيام أحب إلى الله أن يتعبد له فيها من عشر ذي الحجة يعدل صيام كل يوم منها بصيام سنة وقيام كل ليلة منها بقيام ليلة القدر
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[Its chain of transmission is daif]. Ibn Majah also recorded it in the Book of Fasting, chapter on fasting the ten days, hadith 1728, from the hadith of Masud bin Wasil, from him. Nahhas is daif, as stated in Taqrib and elsewhere.