Sayyiduna Umar bin Khattab (may Allah be pleased with him) narrates that when the Messenger of Allah (peace and blessings of Allah be upon him) separated himself from his wives, I said, "O Messenger of Allah, you have stayed in the upper room for twenty-nine days (while you had chosen separation for a month)." So the Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, a month can also be of twenty-nine days."

Sayyiduna Ibn Mas'ud (may Allah be pleased with him) narrates that I have observed twenty-nine fasts with the Prophet (peace and blessings of Allah be upon him) more often than thirty fasts.

Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates that a Bedouin came to the Prophet Muhammad (peace and blessings be upon him) and said, "I saw the moon last night." So the Prophet (peace and blessings be upon him) said: "Do you bear witness that there is no true deity except Allah and that Muhammad (peace and blessings be upon him) is His servant and Messenger?" He replied, "Yes." So the Prophet (peace and blessings be upon him) said: "O so-and-so, stand up and announce among the people that they should fast in the morning."

It is narrated through the chain of Zaidah similar to the above, and it is mentioned that the Prophet ( صلی اللہ علیہ وسلم ) instructed Sayyiduna Bilal (may Allah be pleased with him) to announce among the people.

Sayyiduna ‘Adi bin Hatim (may Allah be pleased with him) narrates that when this verse «‏‏‏‏وَكُلُوا وَاشْرَبُوا حَتَّىٰ يَتَبَيَّنَ لَكُمُ الْخَيْطُ الْأَبْيَضُ مِنَ الْخَيْطِ الْأَسْوَدِ» ‏‏‏‏ [ سورة البقرة: 187 ] “And eat and drink until the white thread of dawn becomes distinct to you from the black thread,”was revealed, the Messenger of Allah (peace and blessings be upon him) said:“Indeed, it is the distinction of the whiteness of the day from the darkness of the night.”

Sayyiduna ‘Adi bin Hatim (may Allah be pleased with him) narrates that I asked,“O Messenger of Allah, what is meant by the black thread and the white thread? Are these two threads?”He (peace be upon him) said:“Indeed, you are broad-necked.”Tell me, have you ever seen two threads? Then he said:“No, rather what is meant is the darkness of the night and the whiteness of the day.”

Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates that the Messenger of Allah (peace and blessings be upon him) said: "There are two types of Fajr. The first Fajr does not make eating unlawful nor does it make the Fajr prayer permissible. Whereas the second Fajr makes eating unlawful and makes the prayer permissible." Imam Abu Bakr (may Allah have mercy on him) says that only Ibn Mihriz narrates this narration from Abu Ahmad.

It is narrated from Sayyiduna Abdullah bin Mas’ud (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said:“None of you should let Bilal’s (may Allah be pleased with him) call to prayer prevent him from eating suhoor, because he gives the adhan so that the one who is sleeping may wake up and the one who is standing in prayer may return (home to eat suhoor).”The Prophet (peace and blessings be upon him) said:“Dawn does not appear in this way (lengthwise), rather it appears in this way, that is, widthwise.”