قال الشيخ رحمه الله فان صلى قبل الوقت متعمدا أعاد وان اخطأ في ذلك فادركه الوقت وهو منها في شئ اجزأته وإن فرغ منها قبل الوقت أعاد
The Shaykh (Al-Mufid), may Allah سبحانه وتعالى support him, said: "If one prays before the time deliberately, he must repeat it. But if he was mistaken in that, and the time enters while he is still in some part of it, it suffices him. And if he completes it before the time, then he must repeat it."
Commentary #2