Salma ibn al-Akwa · The Book of Fasting

"The Messenger of Allah said: 'When you see the crescent then fast, and when you see it, then stop fasting. If it is too cloudy then complete Shaban as thirty days, unless you see the crescent before that, then fast Ramadan as thirty days, unless you see the new crescent before that."'

"Fast when you see it, and stop fasting when you see it, and if clouds prevent you from seeing it, then complete the number, and do not fast ahead of Ramadan."

"We traveled with the Messenger of Allah and some of us fasted and some of us did not."

"When this verse was revealed 'And as for those who can fast with difficulty, (e.g. an old man), they have (a choice either to fast or) to feed a miskin (poor person) (for every day). Those among us who did not want to fast would pay the fidyah, until the verse after it was revealed and abrogated this."