ANSWER:
It was narrated from Abu’l-Maleeh that a man said: I was riding behind the Prophet (peace and blessings of Allaah be upon him) when an animal stumbled. I said: “Woe to the Shaytaan.” The Prophet (peace and blessings of Allaah be upon him) said: “Do not say woe to the Shaytaan, for if you say that he grows bigger until he is like a house, and he says, ‘It is by my power.’ Rather say: ‘Bismillaah (in the name of Allaah),’ for if you say that, he grows smaller, until he is like a fly.” Narrated by Ahmad, 20068; Abu Dawood, 4982; classed as saheeh by al-Albaani in Saheeh Abi Dawood.
The hadeeth is telling us that whenever we curse satan, he is happy because he made us neglectful from remembering Allah after sinning and instead cursing him.