What did the Prophet Muhammad (saw) do when Sa'd mentioned that he used to prolong the first two rak`at and shorten the last two?
 Narrated Jabir bin Samura:                     `Umar said to Sa`d, "The people complained against you in everything, even in prayer." Sa`d replied, "Really I used to prolong the first two rak`at and shorten the last two and I will never shorten the prayer in which I follow Allah's Apostle." `Umar said, "You are telling the truth and that is what I think a tout you."