Sayyiduna Ali (may Allah be pleased with him) said: I heard the Prophet (peace and blessings be upon him) say: "The blood of Ammar and his flesh: it is forbidden for the Fire to consume them."
Al-Bazzar recorded it, and its narrators are thiqat (trustworthy); some of its narrators have a weakness that does no harm.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 15603