Fiqh of Marriage series - What is Mahr and what is the rules of Mahr

What is Mahr?
It is a gift that the shariah has ordained upon the groom to give to his new bride once the Nikah takes place. It could be any amount or any item that is halal e.g. house, car etc. It can be given any time whether during the Nikah ceremony or after the Nikah.
What amount is preferred and mahr Fatimi? Mahr fatimi is preferable but what is the amount? There a difference between Mahr of the Prophets’ wives and his daughter. Mahr Azwaj nabi was 500 dirhams (according to the narration of Aisha ra) and mahr fatimi was 480 dirhams. The Mahr (dowry) of the Messenger of Allāh’s SAW daughters and his wives was five-hundred Dirhams.” (Tabaqāt Ibn Sa’d Vol 8 pg.22) (Except for Umme Habibah which was 4,000 dirhams gifted by Najashi). Abū Dawood
Modern Calculation - Different variations of tolas 130, 132, 150, 152 of silver. 1 tola = 11.664g. However, the preferred conversion units are from dirhams to grams
instead of using tolas.
1 dirham = 3.061g of silver
Mahr Fatimi 480 x 3.061 = 1,469.28g Mahr Azwaj Nabi 500 x 3.061 = 1,530.5g
Other Related Rulings - According to the Hanafi understanding, mentioning the mahr at the time of the Nikah is not necessary nor does it affect the validity of the nikah.