Imam Ja'far al-Sadiq reports from his father (that is, Imam al-Baqir), from his grandfather (Imam Zayn al-Abidin), who said: I found this written on the sword of the Prophet (peace and blessings be upon him): "The person most hateful to Allah Almighty will be the one who kills someone other than his killer (that is, kills someone unjustly), or strikes someone unjustly; and whoever denies the favour of his masters has disowned what Allah Almighty revealed to Sayyiduna Muhammad (peace and blessings be upon him)."
Abu Ya'la recorded it; its chain contains Ibn Ishaq, who is thiqah (trustworthy) but a mudallis; the rest of its narrators are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الفرائض / 7190