The day of Arafat (9th of Dhul Hijjah) will be on Monday (8/20). It is a very blessed day that should not be neglected.
1. Fasting on this day is an expiation for two years.
It was reported from Abu Qutaadah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) was asked about fasting on the Day of Arafat. He said, “It expiates for the sins of the previous year and of the coming year.” (Muslim)
2. It is the day on which the religion was perfected and Allah’s favor was completed.
On the authority of ‘Umar bin al-Khattab, may Allah be pleased with him, that a Jewish man said to him: “O Commander of the Faithful! There is a verse in your Scripture, were it revealed to us Jews we would have taken it as a holiday.” ‘Umar asked, “Which verse?” The man said,
الْيَوْمَ أَكْمَلْتُ لَكُمْ دِينَكُمْ وَأَتْمَمْتُ عَلَيْكُمْ نِعْمَتِي وَرَضِيتُ لَكُمُ الْإِسْلَامَ دِينًا
This day I have perfected your religion for you, completed my favor unto you, and I am pleased to have Islam as your religion. (Quran 5:3)
‘Umar said, “I know the day and place this [verse] was revealed. It was revealed as the Messenger of Allah, peace upon him, was standing on the Mount of Arafa on the Day of Jumu’ah.” (al-Bukhari and Muslim)
3. It is a day by which Allah swore an oath.
And [by] the witness and what is witnessed (Quran 85:3)
Abu Hurairah (may Allah be pleased with him) narrated that the Prophet (peace and blessings of Allah be upon him) said: “The promised day is the Day of Resurrection, the witnessed day is the Day of ‘Arafat, and the witnessing day is Friday.” (al-Tirmidhi)
4. It is the day of forgiveness of sins and freedom from the Fire
‘Aa’ishah (may Allah be pleased with her) narrated that the Prophet (peace and blessings of Allah be upon him) said: “There is no day on which Allah frees more people from the Fire than the Day of ‘Arafat. He comes close and expresses His pride to the angels, saying, ‘What do these people want?’” (Muslim)