Third attempt don't provide a pasuk for Kesef and learn it from beilah and shtar.... Gemara answers those are Baal Karcha but money in ishus can't be Baal karcha.

Now the Gemara has stated that by kiddushin ideally as a ketanah a father should not be mekadesh her as a ketanah however he is allowed to do so directly without selling her as an AMA Ivriyah hoping the koneh will be mekadesh after 6 or when she reaches Naarus..but can arrange eirusin for his ketanah all three ways! As a ketanah she is not a Baal daas to agree!

I believe there's a sugyah in kesubos that is the Eirusin was initiated when she was a ketanah...and before Chupah she reaches Naarus, the father can drag her to the chupah Baal karcha, because when he arranged the eirusin she had no say so her becoming a Naarah doesn't remove his rights over her!

So how can the Gemara say that Keseph can't be utilized based on a kal vchomer because blah e.g. a Naarah Meorasah, or biah on a ketanah arranged by her father is effective and shtar baal karcha is effective when she's a ketanah. I believe that Elazar as a shaliach for Avrahom Avinu (Yitzchak was a Gadol so a father arranging for his Gadol son is a separate question). We know that if Elazar brought back Devorah when she was 3 it was because of kesef shaveh kesef was given to Nachor and he gave her to bring to yitzchak baal Karcha...and there are no mephorshim I'm aware of that says they waited till she was a Naarah for her consent.

Avrahom Kevelson, United States