The Shaykh (Al-Mufid), may Allah سبحانه وتعالى support him, narrated to me from Abu al-Qasim Ja'far ibn Muhammad, from Muhammad ibn Ya'qub, from Muhammad ibn Yahya, from Ahmad ibn Muhammad, from Uthman ibn Isa, from Sama‘ah, who said: I asked Abu Abdullah عليه السلام about a jar in which a dead beetle was found. Imam عليه السلام said: "Remove it and perform Wudu' (ablution) with the water. But if it was a scorpion, pour out the water and use other water for Wudu'." I also asked Imam عليه السلام about a man who has two vessels of water, one of which has been contaminated, but he does not know which one. He cannot access other water. Imam عليه السلام said: "Pour both of them out and perform Tayammum (dry ablution)."