“The news of my observing saum daily and offering salah every night throughout the night reached the Prophet [saws]. So he sent for me, or I met him and he said, ‘I have been informed that you observe saum every day and offer salah every night. Observe saum [for some days] and give it up [for some days] offer salah and sleep for your eyes have a right on you and your body and your family have a right on you.’ I replied, ‘I have more strength than that.’ The Prophet [saws] said, ‘Then observe saum like the saum of Dawud [as].’ I said, ‘How?’ He replied, ‘He used to observe saum on alternate days and he used not to flee on meeting the enemy.’ I said, ‘From where can I get the chance O Allah’s Prophet [saws]?’ So the Prophet [saws] said twice, ‘Whoever observes saum daily throughout his life is just as the one who does not observe saum at all.’”[113]
Prohibited to fast Fridays unless fasted on Thursday or following Saturday
“I [Muhammad bin ‘Abbad bin Ja’far (ra)] asked Jabir bin ‘Abdullah [ra] while he was circumambulating the Ka’bah, ‘Did the Messenger of Allah [saws] forbid fasting on Friday?’ He said, ‘Yes by the Lord of this House.’”[114]
“Do not single out the night of Friday for praying qiyam and do not single out the day of Friday for fasting unless that coincides with a fast that one [habitually] observes [i.e. Ramadan].”[115]
It was reported from Juwairiyah bint Al-Harith [ra] that the Prophet [saws] entered upon her on Friday while she was fasting. He said, “Did you fast yesterday?” She said, “No.” He said, “Do you intend to fast tomorrow?” She said, “No.” He said, “Then break your fast.”[116]
“I [Abu Hurairah (ra)] heard the Prophet [saws] saying, ‘None of you should observe saum on Friday unless he observes saum a day before or after it.’”[117]
“The Messenger of Allah [saws] would fast during the beginning of every month for three days and Friday was the least of the days that he did not fast.”[118]
“The Messenger of Allah [saws] used to fast three days in the middle of every month and he rarely did not fast on Fridays.”[119]
“I [‘Abdullah bin Mas’ud (ra)] rarely saw the Messenger of Allah [saws] not fasting on a Friday.”[120]
Prohibited to fast Saturday by itself
“Do not fast on Saturday except for what has been obligatory upon you [i.e. in Ramadan]. If one of you does not find, but a grape peel or a tree’s twig then let him chew it.”[121]