Sunan Ibn Majah, Volume 2, Book 7, Hadith 1728 (DarusSalam) ⓘ

It was narrated from Abu Hurairah that the Messenger of Allah said: “There are no days in this world during which worship is more beloved to Allah, Glorious is He, than the (first) ten days (of Dhul- Hijjah). Fasting one of these days is equivalent to fasting for one year, and one night of them is equal to Lailatul-Qadr.”

حَدَّثَنَا عُمَرُ بْنُ شَبَّةَ بْنِ عَبِيدَةَ، حَدَّثَنَا مَسْعُودُ بْنُ وَاصِلٍ، عَنِ النَّهَّاسِ بْنِ قَهْمٍ، عَنْ قَتَادَةَ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ‏ "‏ مَا مِنْ أَيَّامِ الدُّنْيَا أَيَّامٌ أَحَبُّ إِلَى اللَّهِ سُبْحَانَهُ أَنْ يُتَعَبَّدَ لَهُ فِيهَا مِنْ أَيَّامِ الْعَشْرِ وَإِنَّ صِيَامَ يَوْمٍ فِيهَا لَيَعْدِلُ صِيَامَ سَنَةٍ وَلَيْلَةٍ فِيهَا بِلَيْلَةِ الْقَدْرِ ‏" ‏ ‏.‏