The Hadith: 'The day on which Allah forgave Adam was the first day of Dhul-Hijjah'

Q: I found a Hadith about the merit of the first ten days of Dhul-Hijjah. It reads as follows: It is related on the authority of Ibn `Abbas that the Prophet (peace be upon him) said: "The day on which Allah forgave Adam (peace be upon him) was the first day of Dhul-Hijjah; so anyone who observes Sawm (Fast) on this day, Allah will forgive all their sins. On the second day, Allah answered the Du`a' (supplication) of Yunus (Jonah, peace be upon him) and took him out of the belly of the whale; so anyone who observes Sawm on this day is like a person who observes `Ibadah (worship) for a year without disobeying Allah for an instant. On the third day, Allah answered the Du`a' of Prophet Zakariyya (Zechariah, peace be upon him); so anyone who observes Sawm on this day, Allah will answer their Du`a'. On the fourth day, `Isa (Jesus, peace be upon him) was born; so anyone who observes Sawm on this day, Allah will save them from (Part No. 3; Page No. 251) suffering and poverty and they will be with the noble, upright, and righteous angels on the Day of Resurrection. On the fifth day, Musa (Moses, peace be upon him) was born; so anyone who observes Sawm on this day will be saved from hypocrisy and the punishment in the grave. On the sixth day, Allah granted His Prophet (peace be upon him) favor; so anyone who observes Sawm on it, Allah will look at them with Mercy and so will never torture them. On the seventh day, the gates of the Fire are closed until the end of the ten days; so anyone who observes Sawm on it, Allah will close for them thirty gates of hardship and open for them thirty gates of ease. The eighth day is called the Day of Tarwiyah (8th of Dhul-Hijjah); so anyone who observes Sawm on it will be given a reward whose magnitude no one knows but Allah (Exalted be He). The ninth day is the Day of `Arafah (9th of Dhul-Hijjah); so anyone who observes Sawm on it, it will be Kaffarah (expiation) for the sins they committed in the past year and the sins they would commit in the coming year. It is the day when Allah revealed His Saying: This day, I have perfected your religion for you, completed My Favour upon you, and have chosen for you Islâm as your religion. The tenth day is the first day of `Eid-ul-Adha (the Festival of the Sacrifice); so anyone who offers Ud-hiyah (sacrificial animal offered by non-pilgrims) on this day, Allah will forgive their sins and that of their children with the first drop of blood to be shed from the sacrificed animal. Moreover, anyone who feeds a believer or gives Sadaqah (voluntary charity) on this day, Allah (Exalted be He) will resurrect them on the Day of Resurrection as safe, and their scales (of good deeds) will outweigh the mountain of Uhud."