Sayyiduna Abdullah bin Amr (may Allah be pleased with him) said: Two men came to Sayyiduna Amr bin al-As (may Allah be pleased with him), disputing over the killing of Sayyiduna Ammar (may Allah be pleased with him) and his belongings. Sayyiduna Amr (may Allah be pleased with him) said: Leave it! For I heard the Prophet (peace and blessings be upon him) say: "The one who kills Ammar and the one who takes his belongings will go to Hell."
Al-Tabarani recorded it; in it the narrator Layth explicitly stated that he heard it directly, and its narrators are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 15619