‏الصيام : Hadeeth No:2501 'A'isha (Allaah be pleased with her) reported. In the pre-Islamic days fast was observed on the day of Ashura, but with the advent of Islam (its position was ascertained as that of a voluntary fast). Then he who wished to fast fasted, and he who liked to abandon it abandoned it....

‏التوبة : Hadeeth No:6654 This hadith has been narrated on the authority of Shu'ba through another chain of transmitters....