The Prophet ﷺ said, "There are no days greater in the sight of Allah, nor more beloved to Him for righteous deeds, than these ten days. So during them, increase your declarations of tahleel, takbeer, and tahmeed."
حدثنا عفان حدثنا أبو عوانة حدثنا يزيد بن أبي زياد عن مجاهد
عن النبي ﷺ قال ما من أيام أعظم عند الله ولا أحب إليه من العمل فيهن من هذه الأيام العشر فأكثروا فيهن من التهليل والتكبير والتحميد
Its chain of transmission is sahih. Tirmidhi alluded to it in 58:2 when he said, "And on this topic..." His commentator said, Abu Awana recorded it in his Sahih.Hafiz also alluded to it in Fath al-Bari 2:381-382, in his commentary on the hadith of Ibn Abbas with similar wording, which will be mentioned later. He noted that Abu Awana narrated it through Musa bin Abu Ayesha from Mujahid, saying "from Ibn Umar" instead of "Ibn Abbas." He then noted that Abu Awana also narrated it through Musa bin Ayun from Amash, saying "from Abu Salih from Abu Hurairah." He said the version preserved as correct in this hadith is the one with Ibn Abbas, intending by this to cast doubt on the narration that mentions Ibn Umar.However, this hadith as found in the Musnad shows that this is in fact a sound and established narration, because Musa bin Abu Ayesha was not alone in narrating it from Mujahid in Sahih Abu Awana. Yazid bin Abu Ziyad corroborated him in this, narrating from Mujahid as well, in the version found here in the Musnad.Abu Awana, the author of the Sahih, is the great, reliable hadith master Yaqub bin Ishaq bin Ibrahim Isfaraini. His Sahih is his mustakhraj on Sahih Muslim, containing many additions, as Dhahabi mentioned in his biography in Tadhkirat al-Huffaz 3:3, 2. This Abu Awana died in the year 316.It should be obvious that he is different from Abu Awana, the teacher of Affan, in the chain of transmission of this hadith. That one is Abu Awana Waddah bin Abdullah Yashkuri, the reliable hadith master, who died in the year 176. Affan said, "Abu Awana's book was sound, containing many dotted and marked letters, and he was reliable." Abu Awana, in all his circumstances, is more sound in hadith to us than Shuba. His biography was given previously at 2124.Something similar to this hadith has already appeared in the Musnad of Ibn Abbas at 1968, 1969, 3139, and 3228. What is meant by "the ten" is the first ten days of Dhul-Hijjah.