What is the ruling on combining a marriage contract with a condition stipulating a specific exchange value?

Primary text

If a person states, 'I married you to my daughter, and here is this one thousand in exchange for two thousand,' the dowry stipulated is invalid. This structure is analogous to the ruling concerning the exchange of one *Madd* of Ajwa dates for two *Madd* of dates, which invalidates the exchange due to usury or disproportionate exchange.