Sayyiduna Anas (may Allah be pleased with him) said: A woman brought poisoned goat meat to the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) ate some of it. Later she was brought, and it was said to him (peace and blessings be upon him): "Shall we kill her?" He (peace and blessings be upon him) said: "No." Sayyiduna Anas (may Allah be pleased with him) said: I always saw the effect of that poison on him (peace and blessings be upon him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 16005