Sulaiman bin Da'ud bin Da'ud سليمان بن داود بن داود بن علي · The Book of Fasting

a Bedouin came to the Messenger of Allah with unkempt hair and said: "O Allah has enjoined upon me of Salah." He said: "The five daily prayers, unless you do any more voluntarily." He said: "Tell me what Allah has enjoined upon me voluntarily." He said: "Tell me what Allah has enjoined upon me of fasting." He said: "Fasting the month of Ramadan, unless you do any more voluntarily." He said: "Tell me what Allah has enjoined upon me of…

A similar, Mursal, report was narrated from 'Ikramah.

"Whoever fasts it and spends its nights in prayer out of faith and in the hope of reward." (Daif)