Sahih Al Bukhari 1.98: Bk 3.41
Narrated Abu Huraira: I said: "O Allah's Apostle! Who will be the luckiest person, who will gain your intercession on the Day of Resurrection?" Allah's Apostle said: O Abu Huraira! "I have thought that none will ask me about it before you as I know your longing for the (learning of) Hadiths. The luckiest person who will have my intercession on the Day of Resurrection will be the one who said sincerely from the bottom of his heart "None has the right to be worshipped but Allah." And `Umar bin `Abdul `Aziz wrote to Abu Bakr bin Hazm, "Look for the knowledge of Hadith and get it written, as I am afraid that religious knowledge will vanish and the religious learned men will pass away (die). Do not accept anything save the Hadiths of the Prophet. Circulate knowledge and teach the ignorant, for knowledge does not vanish except when it is kept secretly (to oneself).

Sahih Al Bukhari 1.507: Bk 9.8-9
Narrated Ghailan: Anas said, "I do not find (now−a−days) things as they were (practiced) at the time of the Prophet." Somebody said "The prayer (is as it was.)" Anas said, "Have you not done in the prayer what you have done? Narrated Az−Zuhri that he visited Anas bin Malik at Damascus and found him weeping and asked him why he was weeping. He replied, "I do not know anything which I used to know during the lifetime of Allah's Apostle except this prayer which is being lost (not offered as it should be).

Sahih Al Bukhari 1.523: Bk 9.25
Narrated Anas bin Malik: We used to pray the `Asr prayer and after that if someone happened to go to the tribe of Bani `Amr bin `Auf, he would find them still praying the `Asr (prayer).

Sahih Al Bukhari 1.524: Bk 9.26
Narrated Abu Bakr bin `Uthman bin Sahl bin Hunaif: that he heard Abu Umama saying: We prayed the Zuhr prayer with `Umar bin `Abdul `Aziz and then went to Anas bin Malik and found himoffering the `Asr prayer. I asked him, "O uncle! Which prayer have you offered?" He said 'The `Asr and this is (the time of) the prayer of Allah s Apostle which we used to pray with him."