Al-Kāfi
Hadith 4229ـ عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ أَحْمَدَ بْنِ أَبِي عَبْدِ الله عَنْ عُثْمَانَ بْنِ عِيسَى عَنْ هَارُونَ بْنِ خَارِجَةَ عَنْ أَبِي عَبْدِ الله (عَلَيهِ السَّلام) قَالَ إِنَّ مِنَ التَّوَاضُعِ أَنْ يَجْلِسَ الرَّجُلُ دُونَ شَرَفِهِ.
Several of our companions narrated from Ahmad ibn Abi Abdullah, from Uthman ibn Isa, from Harun ibn Kharijah, from Abu Abdullah (as), who said: "Verily, humility includes a man sitting below his social rank."