١٨- مُحَمَّدُ بْنُ يَحْيَى عَنْ مُحَمَّدِ بْنِ أَحْمَدَ عَنْ مُحَمَّدِ بْنِ عَبْدِ الْحَمِيدِ عَنْ أَبِي جَمِيلَةَ قَالَ دَخَلْتُ عَلَى أَبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) فَقَالَ لِي يَا شَابُّ أَيَّ شَيْ‏ءٍ تُعَالِجُ فَقُلْتُ الرَّقِيقَ فَقَالَ أُوصِيكَ بِوَصِيَّةٍ فَاحْفَظْهَا لا تَشْتَرِيَنَّ شَيْناً وَلا عَيْباً وَاسْتَوْثِقْ مِنَ الْعُهْدَةِ. 
18. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from Muhammad ibn ‘Abd al-Hamid from abu Jamilah who has said the following: “Once I visited abu ‘Abd Allah , and he asked, ‘Young man, what you do for a living?’ I replied, ‘It is slaves.’ He (the Imam) said, ‘I recommend you so keep my recommendations safe. You must not buy physically or morally defective ones. You must make the guarantees strong and firm.’” 