7-93 Ahmad ibn Zyad al-Hamedany - may God be pleased with him - narrated that Ali ibn Ibrahim ibn Hashim quoted his father, on the authority of Muhammad ibn Abi Umayr and Ali ibn al-Hikam, on the authority of Hisham ibn al-Hakam that Aba Abdullah as-Sadiq (MGB) said, “
In you want to do some good deed such as giving charity, fasting or a similar deed it is best to do it on a Friday since then it would be rewarded twice.”