May the peace, mercy and blessing of Allah be upon you.

A hadith has been related from the Messenger of Allah (may Allah bless him and grant him peace) which mentions that the best kind of fasting was the fasting of Allah`s prophet, Dawud (peace be upon him). Would this fasting fasting on alternate days contradict the Shari`ah of Islam which prohibits fasting on Friday alone or singling out Saturday specifically as a day for fasting? How can a person fast one day and break fast the next without fasting on either Friday or Saturday alone? May Allah reward you well.

May the peace, mercy and blessing of Allah be upon you also.

All praise is for Allah, and may peace and blessing be upon the Messenger of Allah, his family, companions and true followers. To proceed:

Yes, the hadith on the virtue of the fasting of Dawud (David) is authentic; in fact, it is agreed upon. The text of the hadith is as follows: "The Messenger of Allah (may Allah bless him and grant him peace) said, `The most beloved fasting to Allah is the fasting of (the Prophet) Dawud. He used to fast one day and break fast the next day…`" The text of the hadith containing the prohibition of fasting only on Saturday, "The Messenger of Allah (may Allah bless him and grant him peace), `Do not fast on Saturday except for that which has been made obligatory (fard) on you. If any of you find nothing but a grapeskin or a twig from a tree, let him chew on it." This hadith was transmitted by Imam Ahmad, Abu Dawud, and at-Tirmidhi who said, "This hadith is good (hasan); what is disliked is for a man to single out Saturday for fasting, because the Jews hold Saturday sacred (the Sabbath)." It was also transmitted by Ibn Majah, and may Allah have mercy on them all. However, they differed greatly over its authenticity. Supposing it is sahih (authentic), it refers specifically to fasting or intentionally honoring the holy day of the Jews according to most of the scholars. As such, it would be permissible to fast only on Saturday with the intention of fasting in the way the Prophet Dawud (peace be upon him) fasted. It would likewise be permissible to fast on Friday with the same intention. And Allah Almighty is more exalted and more knowledgeable.