Kiddushin 47 - Betrothal with a Loan

If one betroths a woman with a loan, she is not betrothed, for a loan is given to be spent. Thus, a man cannot say to a woman, "I forgive you the loan, and with that money become betrothed to me," because at this time the money is hers. Instead, he can forgive her the loan and betroth her with the benefit she receives from no longer having to repay him.

If a man said to a woman, "Become betrothed to me with $100", but gave her only $1, she is betrothed, and the man must pay later.