The Prophet (peace and blessings of Allah be upon him) said: “The best of marriage is that which is made easiest.” (Narrated by Ibn Hibban, classed as authentic by Al-Albani in Sahih Al-Jami`, 3300)
And he (peace and blessings of Allah be upon him) said: “The best of Mahrs is the simplest (or most affordable).” (Narrated by Al-Hakim and Al-Bayhaqi, classed as authentic by Al-Albani in Sahih Al-Jami`, 3279)
And the Prophet (peace and blessings of Allah be upon him) said to a man who wanted to get married: “Look (for something to give as a dowry), even if it is a ring of iron.” (Narrated by Al-Bukhari and Muslim)
Ibn Majah (1887) narrated that `Umar ibn Al-Khattab (may Allah be pleased with him) said: “Do not go to extremes with regard to the dowries of women, for if that were a sign of honour and dignity in this world or a sign of piety before Allah, then Muhammad (peace and blessings of Allah be upon him) would have done that before you. But he did not give any of his wives, and none of his daughters were given more than twelve Uqiyah. A man may increase the dowry until he feels resentment against her and says, ‘You cost me everything I own, and caused me a great deal of hardship’.” (Classed as authentic by Al-Albani in Sahih Ibn Majah, 1532)
“Do not go to extremes” means do not exaggerate in increasing the dowry. “A man may increase the dowry until he feels resentment against her” means, until he begins to hate her when he is still paying off the debts incurred because of this Mahr because it is too hard for him, or whenever he thinks about the matter. (From Hashiyat As-Sindi `ala Ibn Majah)
The words of Imam Ahmad according to the report of Hanbal imply that it is recommended for the dowry to be four hundred dirhams. This is the correct view in cases where the man can afford it. It is recommended to pay this amount and no more.
In Zad Al-Ma`ad (5/178), Ibn Al-Qayyim (may Allah have mercy on him) quoted some of the Hadiths that indicate that the Mahr should be reduced and that there is no minimum amount. Then he said:
These Hadiths indicate that there is no minimum amount for the Mahr… and that exaggerating concerning the Mahr is disliked, and that it reduces its blessing.
Hence it is clear that what people do nowadays, increasing the Mahr and exaggerating concerning it, is something that goes against the Shari`ah