Al-Kāfi - Volume 7 > Accepting a Bribe for Issuing Judgments
Hadith #3

3- مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنْ مُحَمَّدِ بْنِ سِنَانٍ عَنِ ابْنِ مُسْكَانَ عَنْ يَزِيدَ بْنِ فَرْقَدٍ قَالَ سَأَلْتُ أَبَا عَبْدِ اللهِ (عَلَيْهِ السَّلام) عَنِ السُّحْتِ فَقَالَ هُوَ الرِّشَا فِي الْحُكْمِ.

3. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from Muhammad ibn Sinan from ibn Muskan from Yazid ibn Farqad who has narrated the following: “I once asked abu ‘Abd Allah, ‘Alayhi al-Salam, about al-Suht (sinful earning). He (the Imam) said, ‘It is accepting a bribe to issue judgments.’”