It is narrated from Hazrat Abdullah bin Busr (may Allah be pleased with him) that you are looking at these hands of mine; with these hands I pledged allegiance to the Prophet (peace and blessings be upon him), and the Prophet (peace and blessings be upon him) said: Do not fast on Saturday, except for an obligatory fast. Therefore, if any of you finds nothing but the bark of a tree, then break your fast with that.