This excerpt is taken from Sheikh Farooq Rafi Sahib's book Qurbani, Aqiqa, and Ashra Zil-Hijjah.
Correct evidences from the Book and Sunnah regarding the first ten days of Dhu al-Hijjah have already been mentioned above. However, among the virtues of these days, there are some weak and fabricated narrations as well, which should be avoided from being mentioned or recorded because neither any virtue or merit is established by weak or fabricated narrations, nor is any legal ruling derived from them. Rather, attributing a false narration to the Prophet ﷺ makes the preacher or speaker sinful and liable to severe warning. Below are some weak and fabricated narrations related to the virtues of the first ten days of Dhu al-Hijjah:
① It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them) that the Messenger of Allah ﷺ said:
من صام العشر فله بكل يوم صوم شهر، وله بكل يوم التروية سنة، وله بصوم يوم عرفة سنتان
"Whoever fasts the days of the first ten days of Dhu al-Hijjah, for each day he will have the reward of fasting a month; for the Day of Tarwiyah (8th Dhu al-Hijjah), the reward of fasting a year; and for the Day of Arafah, the reward of fasting two years."
Reference: Kitab al-Mawdu'at by Ibn al-Jawzi: 1137.
This hadith is fabricated as Ibn al-Jawzi has mentioned it in "al-Mawdu'at." Hafiz Ibn al-Jawzi states that this hadith is not authentic. Sulaiman al-Taymi says that in the chain of this hadith, Muhammad bin Saib Kalbi is a lying narrator.
Reference: (Kitab al-Mawdu'at: 526/2)
Imam Bukhari says: Kalbi has been abandoned by Yahya bin Ma'in and Abdur-Rahman bin Mahdi. Then Imam Bukhari narrates on the authority of Yahya from Sufyan that Sufyan said: Kalbi told me: كل ما حدثتك عن أبى صالح فهو كذب "Whatever hadith I narrate to you from Abu Salih is a lie."
Reference: (Mizan al-I'tidal: 577/3)
And in the mentioned chain, Kalbi is narrating from Abu Salih, which is a lie and fabrication from his own mouth.② It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Prophet ﷺ said:
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
"There are no days in which the worship of Allah is more beloved than these ten days of Dhu al-Hijjah. Fasting each day of them is equivalent to fasting a year, and standing in prayer each night of them is equivalent to standing in prayer on the Night of Decree (Laylat al-Qadr)."
Reference: Jami' at-Tirmidhi: 758. Sunan Ibn Majah: 1728. Shu'ab al-Iman by al-Bayhaqi: 3757. Musnad Abi Awana: 3021. Silsilat al-Ahadith al-Da'ifah: 5142. This narration is weak because Mas'ud bin Wasil and Nahas bin Qasam in its chain are weak narrators.
③ Sayyida Aisha Siddiqah (may Allah be pleased with her) narrates:
أن شابا كان صاحب سماع وكان إذا أهل هلال ذي الحجة أصبح صائما، فأرسل إليه رسول الله صلى الله عليه وسلم فقال: ما يحملك على صيام هذه الأيام؟ قال: بأبي وأمي يا رسول الله! إنها أيام المشاعر وأيام الحج عسى الله أن يشركني فى دعائهم، فقال: لك بكل يوم تصومه عدل مائة رقبة تعتقها، ومائة بدنة تهديها إلى بيت الله، ومائة فرس تحمل عليها فى سبيل الله، فإذا كان يوم التروية فذلك عدل ألف رقبة، وألف بدنة وألف فرس تحمل عليها فى Sبيل الله، وصيام سنتين قبلها وسنتين بعدها
A young man was fond of music, but when the moon of Dhu al-Hijjah appeared, he would begin to fast. The Messenger of Allah ﷺ called him and asked: "What motivates you to fast on these days?" He replied: "O Messenger of Allah! May my parents be sacrificed for you. These are the days of Hajj rituals. Perhaps Allah includes me in the prayers of the pilgrims." Upon this, the Prophet ﷺ said: "For you, the reward of each day you fast is equivalent to freeing a neck, sacrificing a hundred camels that you send as sacrifice to the House of Allah, and a hundred horses that you offer as mounts for the path of Jihad. And on the Day of Tarwiyah (8th Dhu al-Hijjah), the reward of fasting is equal to a thousand necks freed, a thousand camels sacrificed, and a thousand horses dedicated for riding in the path of Jihad. And the Day of Arafah (9th Dhu al-Hijjah), the reward of fasting is equal to freeing two thousand necks, sacrificing two thousand camels, and two thousand horses dedicated for Jihad, and the reward is equal to two years of past and future fasting."
Reference: Kitab al-Mawdu'at: 560/2.
Imam Dhahabi says: "This hadith is of the fabricated type and its narrator Muhammad bin Umar al-Muharimi is a very lying person." Muhammad bin Umar al-Muharimi is an abandoned and lying narrator. Abu Hatim says: He is a very weak narrator, and Ibn Ma'in says he has no status in hadith.
Reference: Mizan al-I'tidal: 669/3.
Numerous evidences come in the book and Sunnah regarding the superiority of these two tens (periods). Among them, which is the best ten? The correct and accurate stance on this is that among the days of the whole year, the ten days of Dhu al-Hijjah are the best, and among the nights of the whole year, the last ten nights of Ramadan are the best. Regarding this, the fatwa of Imam Ibn Taymiyyah (may Allah have mercy on him) is very excellent and helpful:
Question: "Which ten days are superior, the ten days of Dhu al-Hijjah or the last ten days of Ramadan?"
Answer: "The first ten days of Dhu al-Hijjah are superior to the last ten days of Ramadan, and the nights of the last ten days of Ramadan are superior to the ten nights of Dhu al-Hijjah."
Hafiz Ibn Qayyim (may Allah have mercy on him) states: "When a learned and intelligent person reflects on this answer, he will find it sufficient and satisfactory because except for the ten days of Dhu al-Hijjah, the deeds of other days are not more beloved to Allah Almighty than the deeds of the ten days of Dhu al-Hijjah. And among these days are the Day of Arafah, the Day of Sacrifice, and the Day of Tarwiyah (which have special virtues). And the last ten nights of Ramadan are nights of vigil in which the Messenger of Allah (peace be upon him) used to worship throughout the night, and among these nights is the Night of Decree (Laylat al-Qadr). Therefore, it is not possible for someone to present a correct argument without this detail."
Reference: Majmoo' Fatawa Ibn Taymiyyah: 287/25.