The Quraysh fasted on the 10th of Myharram/Muharram. Mohammed ordered this too, but later it was optional (Bukhari vol.5 book 58 ch.25 no.172 p.109), also Bukhari vol.6 book 60 ch.24 no.31 p.25.
Hii nayo Muhammad aliagiza ifanyike, lakini baadaye ikawa hiari. (Bukhari juzuu ya 5 kitabu cha 58 sura ya 25 na.172 uk.109), pia Bukhari juzuu ya 6 kitabu cha 60 sura ya 24 na.31 uk. 25.