The Messenger of Allah ﷺ said, "There are no days in which righteous deeds are more beloved to Allah than these days," meaning the ten days of Dhul-Hijjah.The companions asked, "Messenger of Allah, not even striving in the path of Allah?"He replied, "Not even striving in the path of Allah, except for a man who goes out with his life and his wealth and returns with neither."
حدثنا علي بن محمد حدثنا أبو معاوية عن الأعمش عن مسلم البطين عن سعيد بن جبير
قال رسول الله ﷺ ما من أيام العمل الصالح فيها أحب إلى الله من هذه الأيام يعني العشر قالوا يا رسول الله ولا الجهاد في سبيل الله قال ولا الجهاد في سبيل الله إلا رجل خرج بنفسه وماله فلم يرجع من ذلك بشيء
Bukhari narrated it in the Book of the Two Eids, chapter on the merit of good deeds during the days of Tashriq, hadith no. 969, from the hadith of Sulayman Amash, through this chain.