The Book of Good Manners

Riyad as-Salihin, The Book of Good Manners
Book 2, Hadith 690

Narrated 'Abdullah bin 'Amr bin Al-'as (ra):
The Messenger of Allah (pbuh) said, "Four are the qualities which, when found in a person, make him a sheer hypocrite, and one who possesses one of them, possesses one characteristic of hypocrisy until he abandons it. These are: When he is entrusted with something, he betrays trust; when he speaks, he lies; when he promises, he acts treacherously; and when he argues, he behaves in a very imprudent, insulting manner."[Al-Bukhari and Muslim].

Riyad as-Salihin, The Book of Good Manners
Book 2, Hadith 702

Narrated 'Irbad bin Sariyah (ra):
One day, Messenger of Allah (pbuh) delivered a very effective speech, as a result, eyes shed tears and hearts became softened. A man said: "O Prophet of Allah! It sounds as if this is a farewell speech, so advise us." He (pbuh) said, "I admonish you to fear Allah, and to listen and obey even if a black slave has been appointed as your leader. For whoever among you lives after me will see much discord. So hold fast to my Sunnah and the Sunnah of the Rightly-Guided Caliphs who will come after me. Adhere to them and hold fast to them. Beware of Bid'ah (in religion) because every Bid'ah is a misguidance."[Abu Da wud and At-Tirmidhi].