Ahmad ibn Muhammad ibn Isa, from Muhammad ibn Yahya, from Ghiyath ibn Ibrahim, from Jafar, from his father:
Imam عليه السلام said: “That Imam Ali عليه السلام, peace be upon him, used to like breaking the fast upon milk.”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 4, p. 264