Should the amount of Mahr be mentioned in the marriage contract?

Q 1: I witnessed the contracting of a marriage by a Ma’dhun (marriage registrant). When he asked the bride’s Waliy (a legally accountable person acting for a woman regarding marriage) about the Mahr (mandatory gift to a bride from her groom) to record it in the marriage contract document, the Waliy said that they were relatives and there were no conditions between them, and asked him to contract the marriage based on what they had mutually agreed on. The contract was concluded based on what they had agreed on. What is the religious opinion on the lawfulness of this contract?

(Part No. 19; Page No. 53)  A: The contract is valid. It is not a condition of the contract that an amount of money has to be recorded in it. It suffices for the groom and the Waliy to agree on the amount, even if it is not mentioned at the time of concluding the contract. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.