Musnad Ahmad 30:683

Ibrahim ibn Khalid narrated to us, Rabah narrated to us, from Ma'mar, from Yahya ibn Abi Kathir, from Muhammad ibn Abd al-Rahman, from Abu Hurairah, from the Messenger of Allah, may Allah bless him and grant him peace, who said: "Every step he takes toward the prayer, a good deed is written for him by it, and a bad deed is erased from him by it."