Is zakat obligatory on mahr money deposited in a bank, which is not intended for purchasing anything, and if it is obligatory, how is it to be paid?

Zakat must be paid on wealth if it reaches the nisab and a hawl (one lunar year) has passed on it, whether it is cash, gold, or silver, and whether it is from a dowry or other sources, and whether it was saved for travel or building a house. The nisab is equivalent to 85 grams of gold or 595 grams of silver. If the dowry deposited in the bank reaches the nisab or more, zakat must be paid on it whenever a hawl (a Hijri year) passes, by giving out a quarter of a tenth (2.5%). It is not permissible to deposit money in interest-based banks except out of necessity for safekeeping and without earning interest.