Narrated Hudhayfah: The Prophet صلی اللہ علیہ وسلم said: Do not fast (for Ramadan) before the coming of the month until you sight the moon or complete the number (of thirty days); then fast until you sight the moon or complete the number (of thirty days).

Ibn Umar reported the Messenger of Allah صلی اللہ علیہ وسلم as saying“The month consists of twenty nine days, but do not fast till you sight it (the moon) and do not break your fast till you sight it. If the weather is cloudy, calculate it thirty days. When the twenty-ninth of Sha’ban came, Ibn Umar would send someone (who tried) to sight the moon for him. If it was sighted then well and good, in case it was not sighted and there was no cloud and dust before him (on the horizon) he would not keep fast the next day. If there appeared (on the horizon) before him cloud or dust, he would fast the following day. Ibn Umar would end his fasting alone with the people and did not follow this calculation. ”

Narrated Abdullah ibn Abbas: The Prophet صلی اللہ علیہ وسلم said: Do not fast one day or two days just before Ramadan except in the case of a man who has been in the habit or observing a fast (on that day); and do not fast until you sight it (the moon). Then fast until you sight it. If a cloud appears on that day (i. e. 29th of Ramadan) then complete the number thirty (days) and then end the fasting: a month consists of twenty-nine days.

Narrated Ammar: Abu Ishaq reported on the authority of Silah: We were with Ammar on the day when the appearance of the moon was doubtful. (The meat of) goat was brought to him. Some people kept aloof from (eating) it. Ammar said: He who keeps fast on this day disobeys Abul Qasim (i. e. the Prophet) صلی اللہ علیہ وسلم .

Narrated Abu Hurairah: The Messenger of Allah صلی اللہ علیہ وسلم as saying: Do not fast one day or two days just before Ramadan, except in the case of a man who has been in the habit of observing the particular fast, for he may fast on that day.

Narrated Abdullah ibn Umar: The people looked for the moon, so I informed the Messenger of Allah صلی اللہ علیہ وسلم that I had sighted it. He fasted and commanded the people to fast.