The factors that contributed to Tom's initial refusal to the Devil are as follows:
Tom didn't want to accept the Devil's offer because he wasn't sure whether he wanted to make his wife happy by getting all the wealth of Kidd, the pirate. He wanted to snub her because she has caused him so much turmoil over the years. His greed and lust for power was great but his resentment for his wife was greater and this was enough to turn the Devil down on their initial encounter. He is also not afraid of the Devil because his wife has made him so hardened about everything. The Devil has burnt his signature into Tom's forehead to assure him, that he will keep his word. Even though Tom doesn't disclose the terms of the sale of wealth, we can guess that he will probably have to sell his soul to get it.
I'm going to assume you mean Tom's initial refusal to accept the Devil's offer. When Tom is talking to the Devil, he decides he better spend some time thinking about the offer before accepting it, because dealing with the Devil is not something to take lightly. When Tom gets home, he makes a final decision not to deal with the Devil simply to spite his wife. She wants him to take the deal, but Tom will do anything to make his wife angry so he refuses.