Abu Hurairah narrated that:
Allah’s Messenger said: “If it were not that it would be difficult on my nation, then I would have ordered them to use the Siwak for each prayer.”
Jami` at-Tirmidhi, Vol. 1, Book 1, Hadith 22

Narrated Abu Sufyan: That Heraclius sent for him and said, “What did he, i.e. the Prophet (peace be upon him) order you?” I replied, “He orders us to offer prayers; to give alms; to be chaste; and to keep good relations with our relatives. Sahih al-Bukhari, Vol. 8, Book...

Narrated Anas bin Malik:
The Prophet (peace be upon him) drew a few lines and said, “This is (man’s) hope, and this is the instant of his death, and while he is in this state (of hope), the nearer line (death) comes to Him.”
Sahih al-Bukhari, Vol. 8, Book 81, Hadith 7

Samurah bin Jundah narrated that :
Allah’s Messenger said: “Whoever performs Wudu on Friday, then he will receive the blessing, and whoever performs Ghusl then Ghusl is more virtuous.”
Jami` at-Tirmidhi, Vol. 1, Book 4, Hadith 10

Narrated `Abdullah: We used to greet the Prophet (peace be upon him) while he was praying and he used to answer our greetings. When we returned from An-Najashi (the ruler of Ethiopia), we greeted him, but he did not answer us (during the prayer) and (after finishing the prayer) he said...