Hadith 527
Narrated `Abdullah: I asked the Prophet "Which deed is the dearest to Allah?" He replied, "To offer the prayers at their early stated fixed times." I asked, "What is the next (in goodness)?" He replied, "To be good and dutiful to your parents" I again asked, "What is the next (in goodness)?" He replied, 'To participate in Jihad (religious fighting) in Allah's cause." `Abdullah added, "I asked only that much and if I had asked more, the Prophet would have told me more."
Hadith 1200
Narrated Zaid bin Arqam: In the lifetime of the Prophet we used to speak while praying, and one of us would tell his needs to his companions, till the verse, 'Guard strictly your prayers (2.238) was revealed. After that we were ordered to remain silent while praying.
Hadith 2782
Narrated `Abdullah bin Masud: I asked Allah's Apostle, "O Allah's Apostle! What is the best deed?" He replied, "To offer the prayers at their early stated fixed times." I asked, "What is next in goodness?" He replied, "To be good and dutiful to your parents." I further asked, what is next in goodness?" He replied, "To participate in Jihad in Allah's Cause." I did not ask Allah's Apostle anymore and if I had asked him more, he would have told me more.
Hadith 4534
Narrated Zaid bin Arqam: We used to speak while in prayer. One of us used to speak to his brother (while in prayer) about his need, till the Verse was revealed:-- "Guard strictly the (five obligatory) prayers, especially the middle (the Best) (`Asr) Prayer and stand before Allah with obedience (and not to speak to others during the prayers)." Then we were ordered not to speak in the prayers.
Hadith 7534
Narrated Ibn Mas`ud: A man asked the Prophet "What deeds are the best?" The Prophet said: (1) To perform the (daily compulsory) prayers at their (early) stated fixed times, (2) To be good and dutiful to one's own parents. (3) and to participate in Jihad in Allah's Cause."