Hawzah News Agency – Imam Zayn al-Abidin (AS) in his counsel to his son al-Baqir (AS) said:

إيّاكَ يا بُنيَّ أنْ تُصاحِبَ الأحمَقَ أو تُخالِطَهُ، واهْجُرْهُ ولا تُحادِثْهُ؛ فإنّ الأحمَقَ هُجْنَةٌ غائباً كانَ أو حاضِراً، إنْ تَكَلَّم فضَحَهُ حُمقُهُ، وإنْ سَكَتَ قَصُرَ بهِ عِيُّهُ، وإنْ عَمِلَ أفسَدَ، وإنِ اسْتُرعِيَ أضاعَ. لا عِلمُهُ مِن نَفْسِهِ يُغْنيهِ، ولا عِلمُ غَيرهِ يَنْفَعُهُ، ولا يُطيعُ ناصِحَهُ، ولا يَستريحُ مقارِنُهُ، تَوَدُّ اُمُّهُ أنّها ثَكَلَتْهُ، وامْرَأتُهُ أنّها فَقَدتْهُ، وجارُهُ بُعدَ دارِهِ، وجَليسُهُ الوَحْدةَ مِن مُجالَسَتِهِ. إنْ كانَ أصْغَرَ مَن في المَجلِسِ أعْنى‏ مَن فَوقَهُ، وإنْ كانَ أكْبَرَهُم أفْسَدَ مَن دُونَهُ.

'My son, beware of taking a fool as a companion or mingling with him; keep away from him and do not converse with him for verily the fool is a lowly person whether he is absent or present. When he talks he exposes his foolishness and when he is silent he displays his inability to express himself. If he acts he spoils and when he is given responsibility, he fails it. His own knowledge does not suffice him and others' knowledge is of no benefit to him, he does not follow the one who advises him, his associates do not find rest [from him], his mother wishes to be bereaved of him, his wife wishes to lose him, his neighbour wishes to live far from him and the one who sits with him would rather be absent from his company. If he is the lowest [in status] in the gathering he abases those above him and if he is the highest of them he denigrates the others.'

Source: Amali al-Tusi, p. 613, no. 1278