Muhammad ibn Yaqub, from Ali ibn Ibrahim, from his father, from Ibn Abi Umayr, from Hammad, who said:
I (narrator) asked Abu Abdillah عليه السلام, peace be upon him, about ‘the fasting person pouring oil into his ear.’ Imam عليه السلام said: “There is no harm in it.”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 4, p. 328