Yahya bin Hmad bin Aby يحيى بن حماد بن أبي زياد الشيباني · The Book of Fasting

"Raja bin Haiwah narrated that Abu Umamah said: 'I came to the Messenger of Allah and said: Tel l me of something that I may take (learn) from you. He said: "Take to fasting, for there is nothing like it."' '

"O Messenger of Allah, I am a man who fasts continually: shoud I fast when traveling?" He said: "Fast if you wish and break you fast if you wish." 'Ata said: "someone who heard him told me that Ibn 'Umar (said) that the Prophet said: 'Whoever fasts every day of his life, and then he has not fasted."