The insightful and wise do not trust that they are safe from four things: a past sin about which it is not known what the Lord Almighty will do, the remaining lifespan wherein it is not known what destruction lies, some (apparent) advantage a person is given but which could be a lure (from Allāh) in recompense for his wrongdoing, a misguidance that has been beautified – so that he thinks it is guidance – and a momentary deviation of the heart, for a person can be stripped of his religion without realizing it.
Al-Dhahabī, Siyar Aʿlām Al-Nubalāʾ 8:406.
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.
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.
Beware of lying, for lying is far removed from īmān.
Abū Bakr Al-Ḵallāl, Al-Sunnah no. 1467, 1470; Al-Bayhaqī, Shuʿab Al-Īmān no. 4463.
Do not be with the sinner (fājir), for he will beautify to you the things he does, and he will want you to be like him; and he will beautify to you the worst of his practices; and his entrance upon you and leaving from your company will cause ignominy and discredit [of you]. And do not accompany the fool (aḥmaq), for he will exhaust himself [to help you] but will not benefit you, and he may want to benefit you but end up harming you; his silence is better than his speaking, his distance is better than his closeness, and him dying is better than him living. And do not accompany the liar, for life will not benefit you with him, he will tell others what you say, and tell you what others say; and if you speak the truth, it will not be believed.
Abū Bakr Al-Daynūrī, Al-Mujālasah wa Jawāhir AlʿIlm no. 1379.
It used to be said, “People have never honoured themselves with anything [better] than the obedience of Allāh, and they have never dishonoured themselves with anything [worse] than disobedience to Allāh.”
Ibn Abī Al-Dunyā, Muḥāsabatu Al-Nafs article 98.
Stay away from the sinful amongst the scholars and the ignorant amongst the worshippers, for these two are the calamity of everyone who would fall into fitnah.
Al-Bayhaqī, Shuʿab Al-Īmān ḥadīth 1753.
Verily, fear (al-khashyah) is that you fear Allāh such that your fear comes between you and your disobedience (of Allāh). That is khashyah. And dhikr (remembrance) is obedience to Allāh: whoever obeys Allāh has remembered Him; and whoever does not obey Him is not a rememberer of Him, even if he says a lot of tasbīḥ and recites a lot of Qurān.
Al-Dhahabī, Siyar ʾAʿlām Al-Nubalāʾ 4:326.
Boasting that you did a sin (when you did not) is worse than committing the sin.
Al-Daynūrī, Al-Mujālasah wa Jawāhir Al-ʿIlm, article 3073.
When you see someone older than you, say: he has preceded me in īmān and righteous actions so he is better than me; and when you see someone younger than you, say: I have preceded him in sinning and disobedience so he is better than me. And when you see your brothers honouring and revering you, say: this is a virtue they have attained; and when you see them falling short (in their treatment of you) say: this is [because of] a sin I committed.
Ibn Al-Jawzī, Ṣifatu Al-Ṣafwah, article 505: Bakr b. ʿAbdillāh Al-Muzanī.