Making Conditons In The Nikah
Two parties can always enter into any form of contract with whatever conditions they agree to; as long as the conditions are ethical and are not in violation of clear Islamic directives. Once they’re entered into, they are binding on both the parties and each of them will be held accountable for any violation of agreed upon contract because contracts hold a religious sanctity. This is an enough Islamic proof. If someone claims that one cannot put contractual conditions in a contract of Nikah specifically, the burden of proof is on them to prove such prohibition from Islamic sources.