Sayyiduna Jabir (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Whoever testifies that there is no god but Allah Almighty and that I am the Messenger of Allah, his blood becomes lawful only for one of three reasons: one who abandons his religion, a married person who commits fornication, or one who kills a soul unjustly."
Al-Bazzar recorded it. Its chain contains Muhammad bin Abi Layla, who had a poor memory.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الحدود والديات / 10519