Imam Jafer as-Sadiq (as) said, “Saturdays are for us (as). Sundays are for our Shia. Mondays are for our enemies. Tuesdays are for Bani Ummayah. Wednesdays are the days for taking medicine. Thursdays are for taking care of your needs. Fridays are for leaning up and putting on perfume and it is the Eid for the Muslims and is more noble than the Eid ul-Fitr and Eid ul-Adhha. The Day of Eid ul-Ghadeer is the noblest of the holidays and it is on the eighteenth day of the month of Dhul-Hijja. Our Riser (aj) – the Riser (aj) from the Members of the Holy Household – will rise on a Friday. The Resurrection Day will be on a Friday. No deeds are better on Fridays than sending God’s Blessings upon Muhammad (sawa) and his Household (as).

Source: al-Khisaal by Shaikh Sadooq (a.r), Vol. 2, pg. 394, Hadith 101