In his chapter on the mother...
In his chapter on the mother, al-Shafi`i, as well as others, has said: Abu Bakr and Umar, may Allah be pleased with them, never offered sacrifices because they hated others to follow their example and consider doing so as being obligatory. This is an erroneous and a groundless justification; all the sahaba had by then come to know that offering sacrifices was a Sunnah, a commendable act, not an obligation.
Even if we suppose that people thought that they were obligatory, what harm could have resulted especially after having seen how Umar invented the Taraweeh prayers which were neither a Sunnah nor an obligation; rather, the Prophet had prohibited them, yet most “Ahlul Sunnah wal Jama`a” nowadays think that they are obligatory?
By abandoning the Prophet's Sunnah with regard to offering sacrifices, Abu Bakr and Umar may have desired to mislead the people into thinking that not all what the Messenger of Allah had done was obligatory, and that it could be abandoned and ignored. This may explain their statement:…