Ibn ‘Abbaas (may Allaah be pleased with him and his father) reported that the Prophet (peace and blessings of Allaah be upon him) said: “There are no days in which righteous deeds are more beloved to Allaah than these ten days (of Dhul-Hijjah).” The people asked, “Not even jihaad for the sake of Allaah?” He said, “Not even jihaad for the sake of Allaah, except in the case of a man who went out to fight giving himself and his wealth up for the cause, and came back with nothing.” (Reported by al-Bukhaari, 2/457).

‘Abdullaah ibn ‘Umar (may Allaah be pleased with him and his father) reported that the Prophet (peace and blessings of Allaah be upon him) said: “There are no days greater in the sight of Allaah and in which righteous deeds are more beloved to Him than these ten days, so during this time recite a great deal of Tahleel (”La ilaaha ill-Allaah”), Takbeer and Tahmeed.” (Reported by Ahmad, 7/224; Ahmad Shaakir stated that it is saheeh).