[12].Surah Yusuf [Joseph] : Ayat 76

Ayat 76. So he [Yusuf (Joseph)] began (the search) in their bags before the bag of his brother. Then he brought it out of his brother's bag. Thus did We plan for Yusuf (Joseph). He could not take his brother by the law of the king (as a slave), except that Allah willed it. (So Allah made the brothers to bind themselves with their way of "punishment, i.e. enslaving of a thief.") We raise to degrees whom We please, but over all those endowed with knowledge is the All-Knowing (Allah).  

Hazrat Ibn Abbas (May Allah be pleased with them) reported: The Messenger of Allah  [SAWW](PBUH) said, "If I remain alive till the next year, I shall also observe fast on the ninth of Muharram.'' [Muslim Book 06, Chapter 20, Hadith # 2528]. 

Lesson : as mentioned above in Surah Yusuf Ayat 76. "We raise to degrees whom We please,." Some people think these words stand to mean that `he will observe Saum on the 9th of Muharram only. But this interpretation does not agree with other Ahadith. In order to oppose the Jews, he (PBUH) resolved to observe one more Saum with that of 10th of Muharram and ordained it for the Muslims. In this connection, we have quoted above the authority from Musnad Ahmad. Hence, the meanings we have given in the translation of the text are correct.