Britney Spears will not have to ante up any money to estranged husband Sam Asghari, at least based on their prenup, but our sources say there's a big reason she'll feel compelled to write him a substantial check.Sources with direct knowledge of the prenup tell TMZ ... Sam gets no payout in the event of divorce. In addition, the prenup precludes him from getting spousal support. He can keep the gifts Britney gave him and his cars, but that's about it.