What is the ruling on someone who unintentionally broke their fast for one day while observing a two-month fast as expiation for unintentional killing—should they continue their fast or start anew?

If one breaks their fast unintentionally during a fast that requires continuous observance, its continuity is not broken if they make up for that day immediately following their fast. This is the preferred view among the Malikis, and it is the stronger opinion because continuity is achieved by making up for the day immediately. Forgetfulness does not break continuity, based on the Prophet's (peace be upon him) saying: "Indeed, Allah has pardoned for my Ummah their mistakes, their forgetfulness, and what they are coerced into." Furthermore, forgetfulness cannot be guarded against, and Allah does not burden a soul beyond its capacity.