All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Specifying the dowry of the bride in the marriage contract depends on the agreement of both parties. However, one should facilitate it as there are many texts in the Sunnah that encourage minimizing the expenditure of marriage in order to make it easy as this is expected to bring more blessings.
For more benefit on this matter, please refer to Fatwa 87514.
Finally, it should be noted that mentioning the amount of dowry is not a condition for the validity of the marriage contract; Allaah says (what means): {There is no sin on you, if you divorce women while yet you have not touched (had sexual relationship with) them, nor appointed unto them their dowry.}[Quran 2:236]
However, it is desirable to mention the dowry in marriage contracts. If the marriage takes place without mentioning the amount of dowry, then, in this case, the bride deserves the same dowry as other brides of the same social status like her if the bridegroom divorces her or dies.
For more benefit in this regard, please refer to Fatwa 88816.
Allaah Knows best.