You cannot be a scholar unless you have three traits: you do not transgress against those above you, you do not look down on those lesser than you, and you do not take any dunyā in return for your knowledge.
Al-Bayhaqī, Shuʿab Al-Īmān 3:282, article 1655.
A man might have ten qualities, nine of them good and one bad, but the nine good ones can be spoiled by the one bad quality. Beware of the slips and faults of youth.
ʿAbd Al-Razzāq Al-Ṣanʿānī, Al-Muṣannaf 8240.
Beware of dispute and argumentation about the religion, and do not argue with a scholar nor an ignoramus. As for the scholar, he will withhold his knowledge from you, and will not be concerned with what you do. As for the ignorant person, he will only cause roughness in your heart and he will not obey you [anyway].
Al-Dārimī, Al-Sunan no. 302.
I have not seen less zuhd (abstinence) in anything than leadership; you can see a man renouncing food, drink, wealth and clothing, but if his leadership is contested, he vehemently defends and has enmity over it.
Al-Dhahabī, Siyar ʾAʿlām Al-Nubalāʾ 7:262.
Whoever is happy (satisfied) with what Allāh has apportioned for him, it will suffice him and Allāh will bless it for him, but whoever is not satisfied, then [what is apportioned for him] will not suffice him and it will not be blessed.
Ibn Abī Al-Dunyā, Kitāb Al-Riḍā ʿan Allāh bi Qaḍāʾihi article 95.
Do not expose yourself to what does not concern you, stay away from your enemy, beware of [taking as] your friend anyone except the trustworthy amongst people – and there is no one who is trustworthy except one who fears Allāh; and do not accompany the sinner in case you learn his sinfulness, and do not let him know your secrets, and consult those who fear Allāh for your affairs.
Ibn Abī Shaybah, Al-Muṣannaf 34476.
A man does not become noble until he has two qualities: he is undesirous of what other people possess, and he pardons and overlooks them.
Ibn Ḥibbān, Rawḍatu Al-ʿUqalāʾ p167
Do not be from those who are hasty, who broadcast (what should not be broadcast), who plant trouble by divulging what should be secret, for you will face severe, prolonged and heavy tribulations.
Al-Bukhārī, Al-Adab Al-Mufrad no. 327. Its chain of transmission was graded ṣaḥīḥ by Al-Albānī in Ṣaḥīḥ Al-Adab Al-Mufrad no.250.
The victim of theft might continue to suspect and conjecture [about who stole from him] until he becomes worse [in sin] than the thief.
Al-Bukhārī, Al-Adab Al-Mufrad no. 1289. Its chain of transmission was graded ṣaḥīḥ by Al-Albānī in Ṣaḥīḥ Al-Adab Al-Mufrad no.974.
There are three things that I like for myself and for my brothers: That the Muslim man looks to the Qurān; he learns it, recites it, ponders it and refers to it. Second, that he looks to the narrations and the Sunnah; he asks about it and follows it with all his efforts. Third, that he leaves alone all these people except when doing good.
Al-Bukhāri, Al-Ṣaḥīḥ, no. 97 (in annotative, discontiguous form). The chain of transmission is connected in Al-Marwazī, Al-Sunnah, no. 108.