The rule of Ramadhan before we welcome it.

 The rule of Ramadhan before we welcome it.

Alhamdulillah, every Muslim must know the rules of every worship in Islam before he does it so as not to do it out of ignorance and without any reward.

As we know, every deed in Islam is not accepted without intention.

As reported from hadith of Umar ibn Khattab R.A saying,

Every deeds are judged by intentions and everyone will be rewarded according to his intentions.

Sahiih 

And from the hadith,

The mother of the believers, Hafsah (RAA) narrated that The Messenger of Allah (ﷺ) said:

Whoever does not form his intention to fast before to fajr, his fasting will not be accepted.” Related by thefive Imams, but At-Tirmidhi and An-Nasa’i consider it to be related by Hafsah and not connected to the Prophet (ﷺ). Imam Ad-Daraqutni transmitted, "No fasting is accepted for one who does not form the intention (to fast) the night before.”

Bulugh ul Maram.

Book 5, Hadith 677.

So one makes intention before fajr for fasting.

So if the moon of Ramadhan is sighted, one makes intention that night and then wake up the night day to fast.

It is not permissible to sleep and the next day to make intention for one has to fast since he did not make the intention before fajr.

Fasting in the day of doubt where people are in doubt whether the moon is sighted or not.

As reported in hadith,

Narrated Ammar:

AbuIshaq reported on the authority of Silah: We were with Ammar on the day when the appearance of the moonwas 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 AbulQasim (i.e. the Prophet) (ﷺ).

Sunan Abi Dawud 2334.